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Benchmark DAC2 DX
Instruction Manual
Reference Stereo D/A Converter
Native PCM and DSD D/A Conversion
Headphone Amplifier
Asynchronous USB
Dual Output Buses
ESS9018 Conversion System
(Version 2.X Firmware)
Page 2
Safety Information
Fuses
CAUTION: FOR CONTINUED FIRE
HAZARD PROTECTION ALWAYS REPLACE
THE FUSES WITH THE CORRECT SIZE
AND TYPE (0.5A 250 V SLO-BLO® 5 X 20
MM – LITTELFUSE® HXP218.500 OR
EQUIVALENT). THE FUSE DRAWER
INCLUDES TWO FUSES. ALWAYS
REPLACE BOTH FUSES AT THE SAME
TIME.
AC Input Voltage Range
NOTE: THE DAC2 IS EQUIPPED WITH A
UNIVERSAL POWER SUPPLY. THERE IS
NO VOLTAGE SELECTION SWITCH. AC
VOLTAGE RANGE IS 88-264 VAC, 50-60
HZ. THE PRODUCT MAY ALSO BE
OPERATED FROM DC POWER OVER A
VOLTAGE RANGE OF 125-373 VDC.
Power Cord
CAUTION: ALWAYS USE A GROUNDED
POWER CORD. THE PRODUCT IS
EQUIPPED WITH A STANDARD IEC
POWER ENTRY MODULE. USE AN IEC
POWER CORD THAT IS EQUIPPED WITH
THE APPROPRIATE CONNECTOR FOR
YOUR LOCATION. CORDS ARE AVAILABLE
FROM YOUR DEALER.
Modifications
CAUTION: DO NOT SUBSTITUTE PARTS
OR MAKE ANY MODIFICATIONS
WITHOUT THE WRITTEN APPROVAL OF
BENCHMARK MEDIA SYSTEMS, INC.
MODIFICATION MAY CREATE SAFETY
HAZARDS AND VOID THE WARRANTY.
CAUTION: CHANGES OR MODIFICATIONS
NOT EXPRESSLY APPROVED BY
BENCHMARK MEDIA SYSTEMS COULD
VOID THE USER'S AUTHORITY TO
OPERATE THE EQUIPMENT UNDER FCC
REGULATIONS.
Repairs
CAUTION: DO NOT SERVICE OR REPAIR
THIS PRODUCT UNLESS PROPERLY
QUALIFIED. ONLY A QUALIFIED
TECHNICIAN SHOULD PERFORM
REPAIRS.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 2
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Contents
Safety Information 2
Fuses 2
AC Input Voltage Range 2
Power Cord 2
Modifications 2
Repairs 2
Features 4
Introduction 5
Applications 5
DAC2 vs. DAC1 5
DAC2 Technologies 5
Front Panel 9
Rear Panel 9
Quick Start Guide 10
Audio Inputs 10
Remote Control 10
Front Panel Controls 11
Front Panel Displays 12
Headphone Jacks 15
Operational Details 16
DIM and MUTE Functions 16
AUTO-ON Function 16
Bi-directional 12V Trigger 17
CALIBRATED Mode 19
Preamp COMPATIBILITY Mode 20
USB MODE Selection 20
Driving Power Amplifiers 21
HPA2™ Headphone Amplifier 21
Digital Pass-Through 22
Firmware Version Identification 23
Rear Panel 24
Inputs 24
Outputs 27
AC Power-Entry and Fuse Module 28
Internal Settings 29
Jumper-Configured Options 29
Removing Top Cover 29
XLR Output Pads 29
Headphone Switch Configuration 30
Headphone Amplifier Gain 31
Digital PASS-THROUGH Function 32
Calibration Settings 33
Rack Mounting Options 35
Rack-Mount Version of the DAC2 DX 35
Connector Block 35
Premium ½-Wide Blank Rack Panel 36
Black ½-Wide Rack Panel 36
Universal Rack Adapter Tray 36
Rack Mounting Example 37
DAC1 and DAC2 Family History 38
DAC1 Series 38
DAC2 Series 38
Benchmark Technologies 40
Hybrid Gain Control™ 40
Native DSD Conversion 40
High-Headroom DSP 40
32-bit ESS SABRE D/A System 42
Diagnostic Displays 42
Bi-Directional 12 Volt Trigger 42
Distributed Power Regulation 42
HPA2™ Headphone Amplifier 42
Differential Amplifiers 43
Jitter-Immune UltraLock2™ 43
Multi-Mode Asynchronous USB Audio 46
USB Driver Installation 48
Performance Graphs 53
Specifications 69
Audio Performance 69
Group Delay (Latency) 70
Digital Audio Inputs 70
Jitter Tolerance 71
Balanced Analog Outputs 72
Unbalanced Analog Outputs 72
HPA2TM Headphone Outputs 73
Status Display 73
AC Power Requirements 74
Dimensions 74
Weight 74
Regulatory Compliance 75
FCC and RoHS Compliance Statements 75
FCC Notice (U.S. Only) 75
RoHS Compliance Information 75
CE Certificate of Conformity 76
Warranty Information 77
Benchmark 1-Year Warranty 77
Benchmark Extended Warranty Options 78
Notes on Warranty Repairs 78
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 3
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Features
HGC™ (Hybrid Gain Control) – combines motor-driven active analog potentiometers, 32-bit
digital attenuators, and passive analog attenuators, to achieve state-of-the-art performance
ESS SABRE - 32-bit PCM D/A conversion system, four 32-bit D/A converters per channel
ESS SABRE – Native DSD D/A conversion system, four 1-bit DSD D/A converters per channel
Benchmark UltraLock2™ Jitter Attenuation System – eliminates jitter-induced distortion
High Headroom DSP - provides 4 dB of analog and digital headroom above 0 dBFS at an
output level of 24 dBu to completely eliminate the clipping of intersample peaks
Multi-Mode Asynchronous USB Audio 2.0 – 24 bit/192 kHz, DSD (DoP 1.1)
Driverless Asynchronous USB Audio 1.1 – 24-bit/96 kHz
Sample Rate Display – displays the measured sample rate, and format (PCM or DSD)
Word Length Display – displays the measured word length
HPA2™ reference-grade "0-Ohm" headphone power amplifier with dual high-current
outputs
HPA2™ gain jumpers for customizing headphone output gain for headphone sensitivities (Page
31)
2 Headphone Output Jacks – one jack automatically mutes the main outputs, mute feature
can be programmed to mute either output bus and may be disabled (Page 30)
1 AES XLR Digital Input – 24-bit/192 kHz PCM, DSD (DoP 1.1)
2 Coaxial Digital Inputs – 24-bit/192 kHz PCM, DSD (DoP 1.1)
2 Optical Digital Inputs – 24-bit/96 kHz PCM
1 Coaxial Digital Output – digital pass through from USB, Coax, and optical inputs when
function is enabled (Page 32)
3 Stereo Analog Outputs – 1 pair balanced (XLR) plus 2 pairs unbalanced (RCA)
2 Stereo Analog Output Buses – either or both buses can be set to fixed gain
Low-Impedance Passive Output Pads – 0, 10, and 20 dB – optimize balanced output level
to power amplifiers and other downstream devices to maximize system SNR (Page 29)
IR Remote with metal housing provides control of all functions (optional on some models)
Volume-Control Bypass – places one or both analog output buses in a calibrated fixed-gain
mode (Page 19)
Mute – accessible from remote or front panel
Dim – Reduces output level by 20 dB, accessible from remote or front panel
Automatic De-Emphasis – automatically responds to consumer pre-emphasis bit (44.1, 48
kHz)
12V Trigger I/O – bi-directional 12V trigger can act as input, output, or both (Page 17)
AUTO-ON Function - can be programmed to turn on when AC is applied (Page 16)
Power Switch – very low standby power , <0.5 W at 120 VAC
High-Efficiency Low-Noise Power Supplies – only 12-15 W, 88-264 VAC, 50-60 Hz
Meets FCC Class B and CE emissions requirements
Tested for immunity to radiated and conducted RF interference
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 4
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Introduction
Applications
The DAC2 DX is a professional referencegrade audio digital to analog converter with
Benchmark's HPA2™ headphone amplifier.
The DAC2 DX supports 24-bit D/A conversion
of PCM at sample rates up to 192 kHz. It also
supports direct conversion of 1-bit DSD at a
2.8224 MHz sample rate. It is designed to be
very transparent and this makes it well-suited
for critical monitoring in studio control rooms
and mastering rooms.
The DAC2 DX is also well-suited for high-end
hi-fi environments. It includes a generous
collection of inputs and outputs and can serve
as the central component in any stereo hi-fi
system where all inputs are digital. The DAC2
DX provides D/A conversion, source selection,
volume control, and headphone amplification.
A remote control, 12V trigger, and volume
control bypass function provide the features
needed in a home environment.
The DAC2 DX is designed to directly drive a
wide variety of power amplifiers and powered
monitors. The balanced outputs include lowimpedance passive pads that can be adjusted
to optimize the gain staging between the
DAC2 DX and the power amplifier. This gain
optimization can provide very substantial
improvements in the system-level SNR and
THD+N performance.
DAC2 Technologies
Parallel Conversion Structure
The conversion system in the DAC2 DX
achieves a 4.8 dB signal to noise
improvement through the use of 3:1
summing on the main outputs. The ES9018
D/A is an 8-channel 32-bit converter. In the
DAC2 DX, three channels are summed in the
analog domain to form the main outputs. The
remaining two channels provide the auxiliary
outputs.
The 3:1 summing also improves the THD. The
non-linearities in individual conversion
channels are averaged across the four
summed channels and incoherent nonlinearities are attenuated by almost 4.8 dB.
High-Headroom Digital and Analog
Processing
The DAC2 DX has generous amounts of
analog and digital headroom. The analog clip
point is above 29 dBu. The digital clip point is
28 dBu. When operating at a typical -20 dB at
+4 dBu studio calibration, the DAC2 DX has
4 dB of digital headroom above 0 dBFS. This
digital headroom prevents the clipping of
intersample overs.
DAC2 vs. DAC1
The DAC2 adds these features that are not
found on the DAC1:
Asynchronous 192kHz USB Audio 2.0
32-bit D/A conversion system
Word Length Display
Sample Rate Display
Polarity Control
Direct DSD D/A Conversion
-20 dB DIM
Bi-Directional 12V Trigger
Power Switch with Auto-On Function
Volume Control Bypass
Digital Pass-Through
High-Headroom DSP
Dual-Domain Hybrid Gain Control
Additional I/O
No Clipping of Intersample Overs
The DAC2 is one of very few D/A converters
that can accurately reproduce intersample
overs without clipping. Intersample peaks can
reach +3.01 dBFS and commonly occur many
times per second in most 44.1 kHz and 48
kHz recordings. When recordings are ripped
using lossy compression systems (such as
MP3), additional intersample overs are often
created. Most converters (including the
DAC1) produce bursts of distortion at every
occurrence of an intersample over. In
contrast, the DAC2 and DAC3 converters
cleanly reproduce all intersample overs.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 5
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Low-Noise Power Supplies
Asynchronous USB Audio 2.0
The DAC2 DX uses high-efficiency low-noise
power supplies. Each critical subsystem also
has at least one dedicated low-noise
regulator. The high-efficiency supplies deliver
the substantial power required by the lowimpedance circuits, the headphone amplifier,
and the output line drivers. A power switch is
included. The standby power consumption is
less than 0.5 W when the unit is off.
Low Magnetic Emissions
The magnetic components in the DAC2 DX
power supplies operate at over 800 kHz. This
allows the use of very small magnetic
components that emit correspondingly small
magnetic fields. This virtually eliminates all
traces of line-frequency components in the
output spectrum of the DAC2 DX. This also
means that the DAC2 DX can be placed in
close proximity to any audio component
without causing interference with the other
component.
UltraLock2™ Clock System
The USB Audio 2.0 interface supports DSD
and 192 kHz, 24-bit PCM. No drivers are
required for Apple operating systems. Drivers
are provided for older Windows operating
systems at: BenchmarkMedia.com/drivers
Native Asynchronous USB 1.1
The DAC2 DX has a driverless USB Audio 1.1
mode that supports 96 kHz, 24-bit PCM with
all operating systems. This mode provides a
quick and easy connection to a wide variety of
computers and tablets without installing a
driver.
32-bit Digital Gain Control
The DAC2 DX uses the digital section of
Benchmark's dual-domain HGC™ system
(used in the DAC2 HGC).
Benchmark’s unique motor-driven volume
control sets the gain of a 32-bit dithered
digital gain control. The 32-bit digital output
feeds the 32-bit D/A conversion system.
UltraLock2™ provides the outstanding jitter
attenuation of Benchmark's UltraLock™
system while providing an improved SNR.
Dual-Mode USB Input
The DAC2 DX has a USB input that can be
operated in two modes; driverless USB
Audio 1.1, and a high sample rate USB
Audio 2.0. Both use asynchronous clocking
to eliminate the USB interface as a source of
clock jitter.
Note: To provide full backward and forward
compatibility, the DAC2 DX uses the DAC2
USB drivers. This prevents the need to install
two different sets of drivers. Please note that
the DAC2 DX USB input will be identified as
"Benchmark DAC2" in your computer control
panels. This is intentional.
The 32-bit digital gain control delivers low
distortion, accuracy, and precise left-right
gain matching. The noise-free 32-bit dithered
system preserves musical details over a very
wide range of output levels.
The XLR outputs leverage the low-impedance
passive analog attenuation system. When
properly configured, the entire dynamic range
of the DAC2 DX can be lined up with the
dynamic range of the power amplifier. This
matching can provide a dramatic
improvement in the system-level signal to
noise ratio.
The volume control is a servo-driven analog
potentiometer. This control rotates in
response to commands from the remote
control while providing the convenience of
manual adjustments with a physical knob.
The potentiometer produces a DC voltage that
controls the gain of a dithered 32-bit
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 6
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multiplier. The outputs of the multiplier drive
the 32-bit D/A converters.
Low-Impedance Passive Attenuators
Like the DAC1 and DAC2 includes lowimpedance passive attenuators on the XLR
outputs (Page 29).
These attenuators can be adjusted in 10 dB
steps to optimize the interface with the power
amplifier or powered monitors. This
optimization places the volume control in its
best operating range. This exclusive
Benchmark feature can provide substantial
improvements in the overall performance of
the playback signal chain.
Native DSD Conversion
The factory default calibration at 0 dBFS is
+24 dBu on the XLR outputs (pads at 0 dB)
and 2 Vrms on the RCA outputs. If your
studio calibration is different, the calibration
can be adjusted in 1 dB increments from +20
dBu to +28 dBu using the removable jumpers
on connector P6 (Page 33).
The M and/or A lights will be on when the
MAIN and/or AUXILIARY outputs are in the
CALIBRATED mode. A slow flashing light
indicates that a calibrated output is muted.
The DIM function is disabled on any output
group that is operating in CALIBRATED
mode.
When the CALIBRATED mode is off, the M
and/or A lights will flash rapidly when the
volume of the MAIN and/or AUXILIARY
outputs are being adjusted.
The DAC2 DX supports native DSD
conversion. This feature was not available on
the DAC1. DSD signals can be delivered to
the USB or Coaxial inputs in DoP 1.1 format.
The DSD signal is then routed directly to a
bank of 1-bit DSD D/A converters. Three
balanced 1-bit converters are summed
together for each of the MAIN outputs.
Digital Pass-Through
The second coaxial input (D5) can be
reconfigured as a digital output (Page 32).
When D5 is configured as an output, any
selected digital input is passed through to D5
without any processing. Optical, XLR, coaxial,
and USB inputs can be passed through to the
D5 connector. PCM and DoP formatted DSD
can both be passed through the D5 connector
while also being sent to the D/A converter.
The pass-through function even works with
special signals such as DTS, Dolby Digital,
even though these signals cannot be decoded
by the DAC2 DX.
Volume Control Bypass
The CALIBRATED mode can be activated for
either or both output buses (Page 19).
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 7
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The CALIBRATED mode is similar to the
CALIBRATED switch setting on the DAC1
except that the DAC2 DX system is much
more flexible. The DAC2 DX has two
independent output buses that can be
programmed differently. In addition the
settings for these buses are individually
programmable for each digital input on the
DAC2 DX. This flexibility has many
applications in studio and home
environments.
The DAC2 DX will pull the trigger I/O to 12
volts DC while the DAC2 DX is on. If the
DAC2 DX is off and an external device pulls
the trigger I/O to 12 volts, the DAC2 DX will
turn on.
Auto-On Function
The DAC2 DX can be programmed to
automatically turn on when AC power is
applied (Page 16).
Relay-Muted Analog Outputs
The XLR and RCA analog outputs are
equipped with mute relays that keep the
outputs muted while powering on or off.
These relays eliminate pops and clicks at the
unit power up or down.
Bi-directional 12V Trigger
The 12 Volt trigger can be connected to other
audio components so that an entire audio
system can turn on and off in a sequenced
fashion (Page 17).
The DAC2 DX trigger I/O can be connected
to a preamplifier, power amplifier, or both.
Preamp COMPATIBILITY Mode
This feature was added in Version 2.0. If you
have an older version, an update is available.
The COMPATIBILITY mode disables the
volume control when the DAC2 feeds a
preamplifier that will be used to control the
system playback volume. When this mode is
used with a Benchmark preamplifier or line
amplifier, such as the HPA4, a single
Benchmark IR remote can be used to control
both devices (Page 20).
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 8
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Front Panel
Rear Panel
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 9
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Quick Start Guide
OFF
Turns the unit off. Any devices
slaved to the 12V TRIGGER will
also turn off in a controlled
sequence.
Press and hold the OFF button for
3 seconds to force the 12V
TRIGGER off (only necessary
when another device is acting as a
TRIGGER BUS MASTER).
ON
Turns the unit on. Any devices
slaved to the 12V TRIGGER will
also turn on in a controlled
sequence.
VOLUME
Turns the volume up or down.
MUTE
Toggles the MUTE function.
Press and hold the MUTE button
for 10 seconds to toggle the
CALIBRATED mode on the MAIN
outputs.
DIM
Toggles the -20 dB DIM function.
Press and hold the DIM button for
10 seconds to toggle the
CALIBRATED mode on the AUX
outputs.
INPUT
Selects the inputs.
D1
Selects optical digital input D1.
D2
Selects optical digital input D2.
D3
Selects XLR digital input D3.
D4
Selects coaxial digital input D4
then toggles between D4 and D5.
USB
Selects USB input.
Press and hold the USB button for
3 seconds to toggle between the
USB 1.1 and USB 2.0 modes.
Analog
Selects analog input A1 and then
toggles between A1 and A2.
Audio Inputs
The DAC2 DX features six stereo digital
inputs (1 AES XLR, 2 coaxial, 2 optical, and 1
USB). The XLR, coaxial and optical inputs
accept professional (AES), consumer (S/PDIF)
and DoP DSD data formats.
Tip: We recommend using the coaxial or USB
inputs for DSD and for PCM sample rates
above 96 kHz. Optical interfaces are rated for
96 kHz data rates and may not be reliable for
DSD or sample rates above 96 kHz.
Remote Control
The remote control is designed to have a long
operating range. In most applications it is not
necessary to point the remote directly at the
DAC2 DX.
The chart at the right summarizes the
functions of the IR remote control.
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Front Panel Controls
POWER
Turns the unit on or off. Any
devices slaved to the 12V
TRIGGER will also turn on or
off in a controlled sequence.
Starting with the unit off, press
and hold the POWER button
for 10 seconds to set the
AUTO-ON function.
Starting with the unit on, press
and hold the POWER button
for 10 seconds to clear the
AUTO-ON function.
If AUTO-ON is set, the
POWER button will toggle
MUTE on and off (the unit will
remain on).
MUTE
Press once to toggle the -20 dB
DIM function.
Press and hold the MUTE
button for 10 seconds to toggle
the CALIBRATED mode on the
MAIN outputs.
Simultaneously hold the MUTE
and INPUT-UP keys for 10
seconds to activate or
deactivate the
COMPATIBILITY mode.
DIM
Press once to toggle the -20 dB
DIM function.
Press and hold the DIM button
for 10 seconds to toggle the
CALIBRATED mode on the
AUX outputs.
INPUT
Selects the inputs.
Select USB and press lower
button for 10 seconds to toggle
between the USB 1.1 and USB
2.0 modes.
VOLUME
(knob)
Sets the volume of all outputs
that are not in CALIBRATED
mode.
The front panel controls duplicate all of the
functions that are available from the remote
control.
Two additional functions, AUTO-ON, and
COMPATIBILITY mode are only controllable
from the front panel.
The AUTO-ON function keeps the
DAC2 on whenever AC line voltage is
supplied.
The COMPATIBILITY mode disables
the volume control when the DAC2
feeds a preamplifier that will be used
to control the system playback
volume. mote can be used to control
Tip: When AUTO-ON is enabled, a switched
AC outlet can be used to turn your system on
and off. The 12V TRIGGER I/O can be used
as a trigger output to control the power state
of additional components.
The chart at the right summarizes the
functions of the front-panel controls.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 11
both devices.
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Front Panel Displays
A
This light will flash rapidly when the
volume of the AUX bus is being
adjusted.
A solid light indicates that the AUX bus
is in CALIBRATED mode.
A slow-blinking light indicates that the
AUX bus is in CALIBRATED mode but
the output is muted or dimmed.
M
This light will flash rapidly when the
volume of the MAIN bus is being
adjusted.
A solid light indicates that the MAIN
bus is in CALIBRATED mode or in
COMPATIBILITY mode.
A slow-blinking light indicates that the
MAIN bus is in CALIBRATED mode but
the output is muted.
U
A solid light indicates that the USB input
is selected and operating normally.
A blinking light indicates that the input
is selected but a connection to a
computer has not been established.
D1
A solid light indicates that optical input
D1 is selected and operating normally.
A blinking light indicates that the input
is selected but audio data is not being
received.
D2
A solid light indicates that optical input
D2 is selected and operating normally.
A blinking light indicates that the input
is selected but audio data is not being
received.
D3
A solid light indicates that XLR input D3
is selected and operating normally.
A blinking light indicates that the input
is selected but audio data is not being
received.
D4
A solid light indicates that coaxial input
D4 is selected and operating normally.
A blinking light indicates that the input
is selected but audio data is not being
received.
D5
A solid light indicates that coaxial input
D5 is selected and operating normally.
A blinking light indicates that the input
is selected but audio data is not being
received.
There are sixteen status indicator lights on
the front panel. At least one light will be
illuminated whenever power is on.
Calibration and Input Indicators
The M and A indicators
show that the
CALIBRATED mode is
active for the MAIN
and/or AUX outputs.
The input indicators (U
and D1-D5) show which
input is selected.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 12
Note: D5 cannot be selected if the Digital
Pass Through function is enabled.
Instructions for configuring this jumperselected function can be found in the
Internal Settings section of this manual
(Page 29).
Page 13
Input Error Codes
Slow Flash
(2Hz)
No digital signal (output
muted)
Med. Flash
(7Hz)
Data transmission errors or
Non-PCM (output muted)
Rapid flashes
(14Hz)
Non-audio data is being
received (output muted)
Intermittent
flashes
Some data corruption is
occurring, converter may be
interpolating to replace
invalid samples, check the
cable.
MUTE
Indicates that all outputs are
muted.
DIM
Indicates that all non-calibrated
outputs are dimmed by 20 dB.
16 Only
Measured input word length is
16 bits.
16 and 24
Measured input word length is
17 to 23 bits.
24 Only
Measured input word length is
24 bits.
Both Off
Measured input word length is
less than 16 bits.
Digital Format Indicators
An input indicator (U or D1-D5) flash when
an error is present on the selected digital
input. Use the following table to diagnose the
problem:
Tip: Common causes of input errors:
Disconnected or faulty cable
Use of excessively long digital cables
Use of analog cables for digital signals
Use of optical cables for sample rates
exceeding 96 kHz
Incompatible data type (AC3, ADAT, etc.)
Non-audio data is being received
Two lights indicate
the measured word
length of the
selected digital
input.
Four lights indicate
the measured
sample rate and
format of the
selected digital
input.
Tip: Computers, disk players and streaming
devices often subject the digital signal to
sample rate conversion, changes in word
length, PCM to DSD conversions, and other
forms of digital processing that may degrade
the quality of the audio. This display makes it
easy to detect these processes.
Word Length Indicators
The 16 and 24 lights indicate the measured
word length of the selected digital input. The
DAC2 DX detects active data bits and
displays the results as follows:
MUTE and DIM Indicators
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 13
Tip: The DIM button will not change the level
of outputs that are in the CALIBRATED
mode.
Page 14
Format indicators
44 Only
The input format is PCM at a
sample rate of 44.1 kHz (CD
sample rate).
48 Only
The input format is PCM at a
sample rate of 48 kHz (often
used with video).
44 and 2X
The input format is PCM at a
sample rate of 88.2 kHz
(high-resolution audio
format).
48 and 2X
The input format is PCM at a
sample rate of 96 kHz (highresolution audio format).
44 and 4X
The input format is PCM at a
sample rate of 176.4 kHz
(high-resolution audio
format).
48 and 4X
The input format is PCM at a
sample rate of 192 kHz
(high-resolution audio
format).
DSD
(4x and 2X)
The input format is 1-bit DSD
at a sample rate of 2.8224
MHz (high-resolution audio
format). Note: DSD must be
streamed in DoP format.
All Off
Digital signal is not present
or is not in a supported
format.
The 44, 48, 2X, 4X and DSD lights indicate
the sample rate and format of the selected
digital input as follows:
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Headphone Jacks
By default, the lefthand jack mutes the
MAIN outputs.
By default, the righthand jack keeps all
outputs active.
Headphone Mute Switches
Both headphone jacks includes include
switches that can be programmed to mute
the MAIN outputs. When enabled, the MAIN
analog outputs (XLR and RCA) are muted
when a headphone plug is inserted. This
feature allows the listener to switch from
loudspeaker to headphone playback
seamlessly. This Auto-Mute feature can be
disabled or enabled on one or both jacks
using internal jumpers.
Note: Instructions for setting the Auto-Mute
jumpers can be found in the Internal
Settings section of this manual (Page 29).
Tip: The Volume Control simultaneously
adjusts the level for both jacks. If two
listeners will be simultaneously using the
headphone outputs, we recommend using
headphones with identical or similar voltage
sensitivities.
HPA2TM Headphone Power Amplifier
The headphone jacks are driven by
Benchmark's HPA2™ headphone power
amplifier. This very clean power amplifier can
deliver the current and voltage required by
some of the most demanding headphones.
The output impedance of the HPA2™ is very
close to 0 Ohms. This low output impedance
delivers a high damping factor so that the
amplifier can maintain precise control over
the headphone transducers.
Headphone voltage sensitivities vary
substantially, so we have equipped the
HPA2™ with Gain-Range jumpers that can
be used to customize the headphone amplifier
to your favorite headphones. If you find that
you have too much output (volume control
set below 11 o'clock), there are internal
jumpers that can be adjusted to decrease the
output level by 10 dB or 20 dB relative to the
factory default setting.
Note: Instructions for setting the headphone
Gain-Range jumpers can be found in the
Internal Settings section of this manual
(Page 29).
Tip: For optimal performance, the headphone
Gain-Range jumpers should be set so that
comfortable listening levels occur when the
volume control is set above the 11 o'clock
position.
Tip: Use the left-hand jack to mute your
loudspeaker system. Use the right-hand jack
to keep all outputs active.
Driving Two Sets of Headphones
The HPA2™ is specifically designed with
enough power to drive two sets of
headphones.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 15
Page 16
Operational Details
Tip: If the unit is in MUTE, press the DIM
key to immediately enter the DIM mode.
DIM and MUTE Functions
Definition: If the DIM and MUTE and
COMPATIBILITY modes are all off, the
DAC2 DX is in NORMAL mode.
DIM Function
The DIM function reduces the output level by
20 dB. To toggle between NORMAL and DIM
volume, press the DIM button on the remote
or the DIM button on the front panel.
The DIM light will turn on whenever DIM is
active.
The DIM function makes it convenient to fade
back and forth between normal and
background playback volume levels.
If the volume is adjusted while DIM is active,
the NORMAL volume setting will change by
the same amount.
Tip: If the unit is in MUTE and/or DIM press
the ON key (on the remote) to enter the
NORMAL mode.
Tip: if the unit is in DIM, press the MUTE
key to toggle between DIM and MUTE.
AUTO-ON Function
The DAC2 DX can be programmed to
automatically turn on whenever AC power is
applied. This function allows automation using
switched AC outlets. When AUTO-ON is
enabled, the DAC2 DX cannot be turned off
without removing AC power.
The AUTO-ON function is programmed by
pressing and holding the POWER button on
the front panel for 10 seconds. It is the only
function that cannot be programmed from the
remote control. This limitation prevents
accidental access to this special feature.
If an output bus is set to CALIBRATED
mode, DIM is disabled on that bus.
TIP: In the studio, the DIM function allows a
temporary reduction in level without losing
the volume setting that was being used for
monitoring.
Tip: In home applications the DIM function
allows temporary reductions in volume during
TV commercial breaks, phone calls, or other
interruptions, without losing the volume
setting that was being used for normal
listening.
MUTE Function
The MUTE function immediately mutes all
outputs. To toggle this function, press the
MUTE button on the remote or press the
MUTE button on the front panel.
The MUTE light will turn on whenever MUTE
is active.
Enabling AUTO-ON
Starting with the DAC2 DX off, press and
hold the POWER button for 10 seconds.
If AUTO-ON has been successfully enabled,
the POWER button will now function as a
MUTE button. The OFF button on the remote
will also function as a MUTE button when
AUTO-ON is enabled.
Disabling AUTO-ON
Starting with the DAC2 DX on, press and
hold the POWER button for 10 seconds. At
the end of 10 seconds the DAC2 DX will
power down if the AUTO-ON mode has been
successfully disabled.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 16
Page 17
Bi-directional 12V Trigger
Benchmark has reinvented the 12 volt trigger
by adding bi-directional signaling. The trigger
connection on the DAC2 DX can be used as
an input, an output, or both. It is compatible
with any common 12 volt trigger input or
output. The 12V TRIGGER I/O can be used
to turn other audio components on when the
DAC2 DX turns on. The DAC2 DX can also
turn on and off in response to other
connected components. The Benchmark bidirectional 12V Trigger is compatible with
virtually all trigger systems.
The 12V TRIGGER I/O can be connected to
the trigger input or output ports on a
preamplifier, power amplifier, or both.
The DAC2 DX can send a 12 Volt DC trigger
signal to start other components in the
system, or it can wake up in response to an
externally generated trigger signal. The DAC2
DX automatically configures its trigger I/O
port as an input (slave) or output (master).
Trigger Output (DAC2 DX is Master)
12V TRIGGER I/O line to 12 V (after a short
start-up delay).
Trigger Input - (DAC2 DX is Slave)
If the DAC2 DX is off and an external device
pulls the trigger I/O to 12 volts, the DAC2
DX will configure itself as a trigger slave and
will follow the actions of the trigger input. The
DAC2 DX will then turn off when the external
device stops sending the 12 V trigger.
Typical Trigger Applications
In most systems, the 12V TRIGGER will be
used to connect the DAC2 DX to one other
device. The DAC2 DX can be connected to
the first trigger input at the beginning of a
trigger chain, or it can be connected to the
last trigger output at the end of the chain
(less common).
Typical trigger applications:
DAC2 DX → Amplifier
DAC2 DX → Amplifier → Amplifier
DAC2 DX → Preamplifier → Amplifier
When the DAC2 DX is turned on using the
POWER button (on the front panel), or the
ON button (on the remote), the DAC2 DX
configures itself as a trigger master and will
drive the 12V TRIGGER I/O to 12 volts DC
and hold it there while the DAC2 DX is on.
The trigger output signal generated by the
DAC2 DX is delayed so that the DAC2 DX
can stabilize before downstream devices
(such as power amplifiers) turn on. When
powering down, the DAC2 DX will mute
before allowing the trigger line to drop low.
The DAC2 DX keeps the internal power
supplies running for 10 seconds after
dropping the trigger. This delay gives other
triggered components ample time to mute
and shut down.
If the AUTO-ON function is enabled, the
DAC2 DX will automatically turn on when AC
power is applied, configure itself as a trigger
master, and ignore any external signaling on
the 12V TRIGGER I/O line. In AUTO-ON
mode, the DAC2 DX will always drive the
Trigger Bus Applications
The Benchmark bi-directional trigger system
also supports multiple trigger ports wired
together on a bus.
A group of Benchmark trigger ports can be
connected to a group of non-Benchmark
trigger input ports to form a single trigger
bus. A bus should never be connected to
more than one non-Benchmark trigger output
port. If an output port is connected to the
bus, this device should be used to start the
audio system.
A 3.5 mm (1/8") TRS "Y" cable can be used to
split the trigger output of the DAC2 DX to
feed more than one trigger input.
Benchmark AHB2 power amplifiers have two
trigger I/O ports that are wired in parallel.
This makes it easy to connect more than one
power amplifier to a trigger bus (without the
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 17
Page 18
use of a "Y" cord). Connect a trigger cable
between the DAC2 DX and the first amplifier.
Use another trigger cable to connect this
amplifier to the next amplifier. Any number of
Benchmark amplifiers can be added to the
trigger bus. The DAC2 DX will turn on first,
and after a delay, all of the amplifiers will
turn on together.
Maximum input voltage = 30 VDC
Maximum reverse input voltage = -0.3
VDC
Input Impedance = 20 k Ohms
1/8" (3.5 mm) TRS jack
Tip = 12 Volt Trigger I/O
Ring = no connection
Sleeve = chassis ground
Bi-Directional Trigger Applications
Benchmark products support bi-directional
communications over a trigger bus. Any
Benchmark product connected to the bus can
turn the entire system on or off. Because of
the bi-directional design, any power button on
a Benchmark DAC2 DX or AHB2 can be used
to start or stop the system.
The Benchmark device that starts the system
will become the trigger master. If the trigger
master is turned off, all slave devices will
follow. If a slave device is turned off, all other
devices will stay on.
If the DAC2 DX is used to turn the system
on, any connected AHB2 amplifiers will
become slave devices and they can be turned
off without shutting down the DAC2 DX. This
feature makes it easy to turn the AHB2
amplifier(s) off when listening to headphones.
Slave devices can force the entire trigger bus
to shut down if the POWER button or OFF
button is pressed and held for 3 seconds.
Tip: Press and hold the POWER button on
any Benchmark device for 3 seconds to force
a shutdown of the entire trigger-connected
system.
Trigger Specifications
The Benchmark 12V TRIGGER I/O has a
wide operating range to allow interfacing with
most other DC trigger systems. It should only
be used with trigger inputs that are designed
to tolerate 12 VDC.
12 VDC 200 mA current-limited output
Input responds to 3.3 V logic and
higher
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 18
Page 19
CALIBRATED Mode
The CALIBRATED mode sets the MAIN
and/or AUX output buses to calibrated levels.
The two output buses are individually
programmable for each digital input.
The factory preset calibration is +24 dBu at 0
dBFS on the XLR outputs, and 2 Vrms at 0
dBFS on the RCA outputs. The calibration is
adjustable up or down by up to 4 dB in 1 dB
steps using internal jumpers. On the XLR
outputs the calibration range is +20 dBu to
+28 dBu. On the RCA outputs the calibration
range is 1.26 to 3.17 Vrms.
The CALIBRATED mode is similar to the
CALIBRATED switch setting on the DAC1
except that the CALIBRATED mode can be
programmable separately for each input.
The CALIBRATED mode has two distinct
applications:
Volume Control Bypass - useful
when the system has an upstream
digital volume control or a downstream
analog volume control
Calibrated Output - useful in studio
applications where calibrated levels
are needed
CALIBRATED Mode - Volume Control
Bypass
The CALIBRATED mode is useful whenever
the system volume will be controlled before
or after the DAC2 DX. It is usually best to
avoid having two cascaded volume controls in
a playback system. Dual controls will usually
degrade the noise performance of the system
and they can lead to confusion.
If the DAC2 DX feeds a preamplifier, the
preamplifier will provide a downstream analog
volume control for the system and the DAC2
DX should be placed in CALIBRATED mode
for all inputs.
If the DAC2 DX is directly feeding an
amplifier, but one or more sources have
volume controls, the sources with volume
controls can be set to CALIBRATED mode.
Example 1: The USB input is fed from a
computer that has an internal digital volume
control. If you wish to use the volume control
in the computer exclusively, you will want to
enable the CALIBRATED mode on the USB
input. If you do not wish to use the computer
volume control, leave the CALIBRATED
mode off and disable the computer volume
control (or set it to maximum).
The M light indicates that the MAIN bus is in
CALIBRATED mode.
The A light indicates that the AUX bus is in
CALIBRATED mode.
Enabling the CALIBRATED Mode
1. Select the input channel that you wish
to program
2. Press and hold the MUTE button for
10 seconds to toggle CALIBRATED
mode on the MAIN outputs
3. Press and hold the DIM button for 10
seconds to toggle CALIBRATED mode
on the AUX outputs.
Example 2: Digital input D3 is fed from a
digital audio workstation and the workstation
will be controlling the playback level in the
control room. The volume control on the
DAC2 DX will be controlling the playback
level in another room. The MAIN outputs will
be driving the control room monitors and the
AUX outputs will be driving the monitors in
the other room. Select D3 and enable the
CALIBRATED mode on the MAIN outputs
only.
Example 3: Input D4 is being driven by a
music server. A power amplifier in the same
room is driven from the MAIN outputs.
Another room needs a fixed line-level feed to
an integrated amplifier (with volume control).
Select D4 and enable the CALIBRATED
mode on the AUX output only.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 19
Page 20
Preamp COMPATIBILITY Mode
The COMPATIBILITY mode sets the MAIN
output bus to its calibrated output level and
disables the motorized volume control. The
main outputs can then feed a preamplifier
that will be used to control the system
playback volume. When this mode is used
with a Benchmark preamplifier or line
amplifier, such as the HPA4, a single
Benchmark IR remote can be used to control
both devices.
In COMPATIBILITY mode:
M_CAL mode is on for all inputs.
MUTE is disabled.
DIM is disabled.
Remote INPUT select arrows are
disabled.
Remote VOLUME commands are
disabled.
Enabling the COMPATIBILITY mode:
Simultaneously hold the MUTE and
INPUT-UP keys for 10 seconds to
activate or deactivate this feature.
The M light will be illuminated on all
inputs when COMPATIBILITY mode
is enabled.
The DIM and MUTE keys will be
disabled when COMPATIBILITY
mode is enabled.
The DAC2 will not respond to the
DIM, MUTE, VOLUME-UP, VOLUMEDOWN, INPUT-UP, or INPUTDOWN keys on the IR remote when
COMPATIBILITY mode is enabled.
USB MODE Selection
The DAC2 DX supports two USB MODES:
Caution: Close all USB audio playback
applications before changing the USB MODE.
If an audio application is playing while the
USB MODE is changed, the audio application
may freeze.
To change the USB MODE, select the USB
(U) input on DAC2 DX and then press and
hold the USB button on the remote control
for 10 seconds. If a remote control is not
available, select the USB input, and then
press and hold the bottom INPUT button on
the front panel for 10 seconds.
After holding the button for 10 seconds,
either the 4X lamp or the 2X lamp will flash
once indicating the new USB MODE. A flash
of the 4X lamp indicates that the unit is now
in USB Audio 2.0 mode. A flash of the 2X
lamp indicates that the unit is now in USB
Audio 1.1 mode.
Tip: The 4X or 2X lamp will flash once every
time the USB input is selected. This flash
provides a convenient indication of the
current USB MODE.
Tip: Avoid any unnecessary switching
between USB MODES. Rapid switching
between modes can confuse some operating
systems.
Tip: USB Audio 1.1 and USB Audio 2.0 are
industry standard protocols for the
transmission of digital audio over USB
interfaces. Mac operating systems and
Windows operating systems starting with
Windows 10 support both modes. Windows
operating systems prior to Windows 10 only
support USB Audio 1.1. For this reason, we
provide a Windows driver for USB Audio 2.0
that can be used with older Windows
systems. Do not attempt to install this driver
on Windows 10 systems.
USB Audio 1.1 mode - up to 24 bits
at 96 kHz
USB Audio 2.0 mode - up to 24 bits
at 192 kHz plus DSD in DoP 1.1 format
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 20
Page 21
Driving Power Amplifiers
The DAC2 DX is designed to directly drive
virtually any audio power amplifier or
powered monitor. This direct connection
provides the cleanest and shortest path from
the digital source to the monitor output.
Tip: In most cases, Benchmark does not
recommend placing an audio device between
the DAC2 and the power amplifier. One
notable exception is the HPA4 line amplifier.
The HPA4 provides stepped relay gain control
with exceedingly low THD and noise. The
HPA4 provides the ultimate analog volume
control and it can operate transparently
between the DAC2 and a power amplifier.
The RCA and XLR outputs on the DAC2 DX
are equipped with low-impedance highcurrent drivers. These robust outputs are well
equipped to drive a wide variety of input
impedances. The DAC2 DX outputs remain
clean when driving amplifiers that present
difficult loads (high input capacitance and/or
low input impedance).
The XLR outputs on the DAC2 DX are
equipped with jumper-configured passive lowimpedance output pads. These pads can be
set to an attenuation of 0 dB (pad off), 10
dB, or 20 dB. The pads should be used to
match the output level of the DAC2 DX to the
input sensitivity of the power amplifier. Most
power amplifiers and powered monitors will
require the use of the 10 dB or 20 dB pads.
Use the high-output 0 dB setting when
driving a Benchmark AHB2 power amplifier.
between the DAC2 DX and the AHB2 while
placing the DAC2 DX volume control in the
proper range.
Tip: If you are using a DAC2 DX with non-
Benchmark power amplifiers, the XLR pads
should be set so that comfortable listening
levels occur when the VOLUME control is set
above 11 o’clock. This will optimize the gainstaging between the DAC2 DX and your
power amplifier.
Tip: Increase the pad setting if a comfortable
listening level is reached at a VOLUME
control setting below the 11 o'clock position.
Tip: Decrease the pad setting if a comfortable
listening level cannot be reached when the
VOLUME control is fully clockwise.
Instructions for setting the XLR pad jumpers
are detailed in the Internal Settings section
of this manual (Page 29).The DAC2 DX is
shipped with the XLR pads disabled (set to 0
dB). No adjustments will be necessary if you
will be using a Benchmark AHB2 power
amplifier.
HPA2™ Headphone Amplifier
The DAC2 DX is equipped with two 1/4"
stereo headphone jacks. The audio output on
both jacks is wired in parallel and is driven by
Benchmark's HPA2™ headphone power
amplifier. The HPA2™ is an ultra-clean power
amplifier that is capable of delivering 1.25 W
into 30 Ohms. It easily drives a pair of
headphones.
Tip: The Benchmark AHB2 power amplifier
has a unique low-gain topology that allows it
to accept full studio-level input signals. This
high-level interconnection provides a very
low-noise connection between the DAC2 DX
and the AHB2. Set the input SENSITIVITY
switch on the AHB2 to 22 dBu (all the way
down). This places the AHB2 full-power
output point at an input level of 22 dBu. This
level is exactly 2 dB lower than the
CALIBRATED output level of the DAC2 DX
(when the pads are set to 0 dB). This
configuration optimizes the gain-staging
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 21
Both headphone jacks are equipped with mute
switches that can be programmed to mute the
analog outputs on the back of the DAC2 DX.
By default, the switch on the left-hand
headphone jack is enabled and the switch on
the right-hand headphone jack is disabled.
Instructions for setting the headphone
switches are detailed in the Internal
Settings section of this manual (Page 29).
The HPA2™ is one of the most transparent
headphone amplifiers available. It also is able
Page 22
to deliver high current and/or high signal
levels making it well suited for a wide variety
of headphones. The near 0-Ohm output
impedance provides outstanding damping of
headphone drivers. This damping reduces
distortion while maintaining precise control of
the frequency response at the output of the
amplifier.
Digital Pass-Through
The second coaxial input (D5) can be
reconfigured as a digital output. When
operating as an output, any selected digital
input is passed through to D5 without any
processing.
The HPA2™ has a set of 3-position gain-range
jumpers that can be used to increase or
decrease the gain by 10 dB relative to the
factory calibrated setting.
The jumpers change the gain of the HPA2™
headphone amplifier without changing the
output impedance. This keeps the output
impedance of the HPA2™ constant and very
near 0 Ohms. External attenuators should
never be inserted after a headphone amplifier
as this would change the output impedance
and alter the frequency response of the
headphones.
Proper gain settings are important for
maximizing the SNR of the headphone
monitoring system. With proper settings, the
full performance of the DAC2 DX can be
delivered to the headphones for critical
monitoring tasks and for maximum musical
enjoyment.
Tip: When the headphone gain jumpers are
set properly, a normal listening level will be
achieved at a VOLUME control setting above
the 11 o'clock position.
Tip: If a normal listening level is achieved
below an 11 o’clock VOLUME setting, the
headphone gain is too high, and the gain
should be decreased.
Optical, coaxial, and USB inputs (U, D1, D2,
D3 and D4) can be passed through to the D5
connector. The signals are buffered but are
not processed in any way. For this reason,
any data format can be passed through to the
D5 connector, even when these formats
cannot be decoded by the DAC2 DX.
Surround formats, such as DTS, Dolby Digital,
cannot be decoded by the DAC2 DX, but they
can be passed to a surround system using the
digital pass-through function.
The digital pass-through can also be used to
provide the following digital signal
conversions:
Optical to Coaxial
USB to Coaxial
AES XLR Digital to Coaxial
Coaxial to Coaxial (buffering)
DoP encapsulated DSD can also be passed
through D5. For example, DSD files on a
computer can be sent in DoP to the USB
input on the DAC2 DX. The USB input can be
routed to coaxial output D5. This output can
be recorded by any 24-bit, 176.4 kHz digital
recorder with a coaxial input. The PCM digital
recorder can then be used to play the DSD
recordings in DoP format.
Tip: If the level is too low at the maximum
VOLUME setting, the headphone gain is too
low, and the gain should be increased.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 22
Page 23
Firmware Version Identification
Digit 1
Digit 2
8
D1 D2
.8
4 U
D3
.4
2 M
D4
.2
1 A
D5
.1
The firmware version is displayed during the
lamp test while the DAC2 is turning on. At
least one lamp in the INPUT INDICATOR
will flash rapidly while the remaining lamps
will be on. The flashing lamps identify the
firmware version. The values of each lamp
are shown in this chart below.
Add the values of all flashing lamps to
determine the version number. If no lamp
flashes in the second column, the second digit
is a 0.
Example 1: The A lamp is the only lamp that
flashes. The firmware version is 1.0.
Example 2: The A and D5 lamps flash. The
firmware version is 1.1.
Example 3: The M lamp is the only lamp that
flashes. The firmware version is 2.0.
Example 4: The M, A, D5, D4 and D3 lamps
flash. The firmware version is 3.7.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 23
Page 24
Rear Panel
Inputs
There are six stereo digital inputs on the
DAC2 DX:
USB - USB Audio 1.1 or 2.0 Input
D1 - Optical Digital Input
D2 - Optical Digital Input
D3 - XLR Digital Input
D4 - Coaxial Digital Input
D5 - Coaxial Digital Input or Output*
These inputs are selected using the INPUT
buttons on the front-panel or on the remotecontrol.
Tip: There is no D5 button on the remote
control. Use the INPUT up-down buttons or
press D4 twice to select input D5. Pressing
D4 again to return to input D4.
* D5 can be jumper-configured as a digital
PASS-THROUGH output. When enabled, the
selected digital input will be routed to the
internal D/A converter and to output D5. The
selected input will be buffered and sent to
output D5 even if the format cannot be
decoded by the DAC2 DX.
The digital inputs support PCM stereo
AES/EBU and SPDIF digital formats. Maximum
word length is 24-bits. Maximum sample rate
is 192kHz. The digital inputs also support
DSD stereo at a sample rate of 2.8224 MHz
using DoP 1.1 encapsulation.
The USB input has two operating modes:
USB Audio 1.1 - PCM up to 24-bits at
96 kHz
USB Audio 2.0 - PCM up to 24-bits at
192 kHz and DSD (DoP 1.1 format)
Caution: The optical inputs (D1 and D2) are
not recommended for DSD or for sample
rates above 96 kHz. Optical connections may
be unreliable at sample rates above 96 kHz.
Tip: The DAC2 DX will not decode
multichannel digital formats such as AC3, and
Dolby Digital. The audio will mute and the
INPUT INDICATORS will flash whenever an
incompatible format is connected to the
selected digital input. If the PASS-THROUGH
mode is enabled, these multichannel formats
can be sent to a surround processor using
connector D5 as a digital output.
Caution: The 12V TRIGGER I/O is not an
audio connection! This is a 12V DC connection
for synchronizing the on and off sequencing of
an entire audio system.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 24
Page 25
Digital Inputs - Details
All of the digital inputs on the DAC2 DX use
Benchmark's UltraLock2™ system to remove
virtually all of the interface jitter. The result is
that all digital inputs deliver identical audio
performance. The USB, optical, XLR and
coaxial digital inputs will all sound identical if
they receive identical data.
Computer Input – USB
The USB Audio 2.0 mode was tested for
compatibility with Windows XP, Vista, 7, and
8 (driver installation is required for these
Windows versions). Beginning with Windows
10, no driver is required. Do not attempt to
install the driver on Windows 10.
The USB Audio 2.0 mode was also tested for
compatibility with Mac OS X starting with
version 10.6 (operation is driverless for all OS
X versions).
The USB input accepts a Type-B male USB
connector. A Type-A to Type-B USB cable is
provided with the DAC2 DX. The USB cable
connects the DAC2 DX directly to a
computer’s USB output.
The USB input supports 44.1, 48, 88.2, 96,
176.4, and 192 kHz PCM sample rates at
word lengths up to 24-bits. The USB input
also accepts DSD in DoP 1.1 format.
The DAC2 DX can be configured as a USB
Audio 1.1 or USB Audio 2.0 device. Press
and hold the USB button on the REMOTE for
10 seconds to toggle the USB MODE. If a
remote is not available, select the USB input
and then press and hold the bottom INPUT
button on the front panel for 10 seconds.
The USB AUDIO 1.1 mode never requires
the installation of a driver. It allows a quick
driverless connection to Windows machines
when playing sample rates of 96 kHz or less.
In this mode, Windows machines can begin
streaming audio within seconds after the
DAC2 DX is connected for the first time. No
software or hardware configuration is usually
required.
Optical Digital Inputs - D1 and D2
The optical input connectors (D1 and D2) are
commonly known as TOSLINK connectors.
The TOSLINK optical connectors used on the
DAC2 DX are designed to work well at
sample rates up to 96 kHz. Maximum word
length is 24-bits. All sample rates between 28
and 96 kHz are supported. The optical inputs
may be unreliable at sample rates above 96
kHz. The optical inputs will accept
professional AES/EBU data formats or
consumer S/PDIF data formats.
Tip: The optical inputs include dust caps.
Keep these in place if the input is not being
used.
XLR Digital Input - D3
The XLR digital inputs (D3) uses a female XLR
connector. The input impedance is 110 Ohms.
Maximum word length is 24-bits. All sample
rates between 28 and 195 kHz are supported.
The XLR digital input will accept professional
AES/EBU data formats or consumer S/PDIF
data formats. The XLR input also accepts DSD
in DoP 1.1 format.
USB Audio 2.0 is required for DSD and for
all PCM sample rates exceeding 96 kHz.
Windows computers require a driver to
support the USB Audio 2.0 mode.
The USB Audio 1.1 mode was tested for
compatibility with Windows XP, Vista, 7, 8
and 10, Mac OS X, and iPads using the 30-pin
to USB Camera Kit. No driver installation is
required for any of these systems when
operating in USB Audio 1.1 mode.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 25
The XLR digital input is transformer coupled.
The transformer provides galvanic isolation of
the signal pins (2 and 3). A capacitor protects
the transformer from DC currents. Diodes at
the transformer outputs protect the digital
audio receiver. Pin 1 (ground) and the XLR
shell are tied directly to the chassis to prevent
currents in the internal ground system. This
direct bonding also maximizes RF shielding.
Page 26
Caution: Use 110-Ohm digital audio cables
for digital XLR audio connections. Do not use
analog XLR cables. Digital interfaces require
the use of matched impedances. The digital
input may not function, or may be unreliable
if the incorrect cable is used.
Coaxial Digital Inputs - D4 and D5
The coaxial digital inputs (D4 and D5) use
female RCA connectors. The input impedance
is 75 Ohms. Maximum word length is 24-bits.
All sample rates between 28 and 195 kHz are
supported. The coaxial digital inputs will
accept professional AES/EBU data formats or
consumer S/PDIF data formats. The coaxial
inputs also accept DSD in DoP 1.1 format.
12V TRIGGER I/O
The Benchmark bi-directional 12V TRIGGER
is compatible with virtually all trigger
systems. The 12V TRIGGER I/O connection
on the DAC2 DX can be used as an input, an
output, or both. It is compatible with most 12
volt trigger inputs and outputs. The 12V
TRIGGER can be used to turn other audio
components on when the DAC2 DX turns on.
The DAC2 DX can also turn on and off in
response to trigger signals sent from other
components.
The 12V TRIGGER I/O can be connected to
the trigger input or output ports on a
preamplifier, power amplifier, or both.
The coaxial digital inputs are DC isolated,
current limited, and diode protected. The RCA
body is bonded directly to the chassis to
prevent currents in the internal ground
system. This direct bonding also maximizes
RF shielding.
Caution: Use 75-Ohm coaxial cables for
digital audio connections D4 and D5. Digital
interfaces require the use of matched
impedances. Do not use 50-Ohm coaxial
cables, twisted pair cables, or any non-coaxial
cables for digital audio. The digital inputs may
not function, or may be unreliable if the
incorrect cable is used.
Note: The Coaxial inputs (D4 and D5) accept
professional or consumer digital audio
formats. The AES3-id and SMPTE 276M
standards specify a 75-Ohm, 1 Vpp,
professional format which is also known as
AES/EBU and is commonly used in video
production facilities. The IEC 609588-3
standard specifies a 75-Ohm, 0.5 Vpp,
consumer format which is also known as
S/PDIF, and is commonly used in hi-fi
equipment. The coaxial inputs are designed to
accept either type of signal.
The DAC2 DX can send a 12 Volt trigger
signal to start other components in the
system, or it can wake up in response to an
externally generated trigger signal. The DAC2
DX automatically configures the 12V
TRIGGER I/O port as an input (slave) or
output (master). See the Bi-directional 12V
Trigger section on Page 17 for more
information.
The Benchmark 12V TRIGGER I/O has a
wide operating range to allow interfacing with
most other DC trigger systems. It should only
be used with trigger inputs that are designed
to tolerate 12 VDC.
12 VDC 200 mA current-limited output
Input responds to 3.3 V logic and
higher
Maximum input voltage = 30 VDC
Maximum reverse input voltage = -0.3
VDC
Input Impedance = 20 k Ohms
1/8" (3.5 mm) TRS jack
Tip = 12 Volt Trigger I/O
Ring = no connection
Sleeve = chassis ground
Caution: The 12V TRIGGER I/O is not an
audio connection! This is a 12V DC connection
for synchronizing the on and off sequencing of
an entire audio system.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 26
Page 27
Outputs
Analog Outputs
Balanced XLR Analog Line Outputs
The DAC2 DX has two analog output buses
(MAIN and AUX). By default, both buses are
controlled by the volume control. Either or
both buses can be programmed to bypass the
volume control. The CALIBRATED mode
bypasses the volume control and sets the
output(s) to a preset level.
MAIN Bus
The MAIN bus drives the XLR outputs and
one pair of RCA outputs. The MAIN bus
delivers the highest performance because it
uses three conversion channels wired in
parallel for each XLR connector. The main bus
uses 6 of the 8 channels in the ES9018 D/A
conversion chip. The remaining two channels
in the ES9018 drive the AUX bus.
AUX Bus
The AUX bus drives the second pair of RCA
outputs.
The Left and Right balanced outputs use
Neutrik™ gold-pin male XLR jacks. The XLR
shell and pin 1 (ground) are both directly
bonded to the chassis to prevent currents in
the internal ground system. This direct
bonding also maximizes RF shielding.
The XLR outputs have passive attenuators
that allow direct connections to a wide variety
of audio devices without a loss of dynamic
range. The 10 or 20 dB pads are usually
required for direct interfacing to power
amplifiers and powered speakers. The DAC2
DX ships with the pads disabled (0 dB
setting). Use the 0 dB setting with the
Benchmark AHB2 power amplifier. A full
description of the output attenuators and
instructions for configuration is located in the
Internal Settings section of this manual
(Page 29).
Industry-Standard XLR Wiring
XLR pin 2 = + Audio Out
XLR pin 3 = - Audio Out
XLR pin 1 = Cable Shield
Output Drivers
The DAC2 DX features high-current output
drivers that are capable of driving 300-Ohm
loads without an increase in distortion. They
are also well suited for driving long cables or
high-capacitance loads.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 27
Caution: If the balanced XLR outputs are
wired to an unbalanced input (using a special
adapter cable), pin 3 must be left floating.
Shorting pin 3 to ground will increase the
temperature of the output drivers, will
increase power consumption, may cause
distortion, and may shorten the life of the
output drivers.
Page 28
Unbalanced RCA Analog Outputs
Input Voltage Range
Note: The DAC2 DX is equipped with a
universal power supply. There is no voltage
selection switch. AC voltage range is 88-264
VAC, 50-60 Hz.
Power Cord
The Left and Right unbalanced outputs use
female RCA jacks. The ground connections
are bonded to chassis ground at the location
where analog ground is bonded to the
chassis. This minimizes the effects of ground
loops caused by AC currents in the cable
shield. The RCA output impedance is very low
(30 Ohms). This makes these outputs well
suited for driving high-capacitance loads
and/or high-capacitance cables.
Caution: Mono summing with an RCA ‘Y’
cable is not recommended as this can cause
high amounts of distortion. Mono summing
with a ‘Y’ cable can be accomplished with the
use of a modified cable by implementing a 1k
Ohm series resistor in each leg of the ‘Y’.
Note: The XLR pads do not have any effect
on the level of the RCA outputs.
AC Power-Entry and Fuse Module
Note: The AC power input uses a standard
IEC type connector. One USA-compatible
power cord is included with DAC2 DX
converters. IEC style power cords in countryspecific configurations are available in your
locality.
Caution: Always use a grounded power
cord. The DAC2 DX is equipped with a
standard IEC power entry module. Use
an IEC power cord that is equipped with
the appropriate connector for your
location. Cords are available from your
dealer.
Fuses
Caution: For continued fire hazard
protection always replace the fuses with
the correct size and type (0.5A 250 V
Slo-Blo® 5 x 20 mm – Littelfuse®
HXP218.500 or equivalent). The fuse
drawer includes two fuses. Always
replace both fuses at the same time.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 28
Page 29
Internal Settings
Balanced Output Drive Capability:
Attenuator Output Maximum Loss in dB
Setting (dB) Impedance Cable (ft) at 20 kHz
0 60 680 0.1
10 425 96 0.1
20 135 302 0.1
Unbalanced Output Drive Capability:
Output Maximum Loss in dB
Impedance Cable (ft) at 20 kHz
30 1360 0.1
XLR Output Pads
Jumper-Configured Options
The following functions are jumper
configured:
XLR Output Pads
Headphone Mute Switches
Headphone Gain
Digital Pass-Through
Calibration Level
Removing Top Cover
The DAC2 DX cover must be removed to gain
access to the jumpers. Do not attempt to
remove the faceplate or rear panel.
Caution: The DAC2 DX contains static
sensitive components. Static discharge may
cause component failures, may affect the
long-term reliability, or may degrade the
audio performance. Use a static control wrist
strap when changing jumper settings.
Disconnect AC power by unplugging
the power cord at the back of the
DAC2 DX.
Remove the 8 screws holding the
cover (4 on each side).
Do not remove any screws on the
front, rear, or bottom panels!
Never remove the power entry safety
cover in the rear corner of the DAC2
DX.
Always connect a static-control wrist
strap to the chassis before touching
any internal component.
The XLR outputs are equipped with lowimpedance passive pads that may be used to
reduce the output levels while preserving the
full dynamic range of the DAC2 DX. The
DAC2 DX ships with the pads disabled (0 dB
setting).
Tip: The XLR outputs are factory-preset to
deliver professional studio levels. Most power
amplifiers and powered monitors will require
the use of the 10 dB or 20 dB pads.
Tip: Use the factory-default 0 dB setting with
Benchmark's AHB2 power amplifier. When
directly driving most other power amplifiers
(or powered speakers), start with the 10 dB
pad setting. If necessary, change the pads so
that normal listening levels are achieved
when the VOLUME control is between the 11
o’clock and 3 o'clock positions.
When the output pads are enabled, the
output impedance changes slightly, and the
maximum recommended XLR cable length is
reduced as shown in Table 1. The table
assumes a cable capacitance of 32 pF/foot
and a maximum allowable loss of 0.1 dB at 20
kHz.
Table 1 - Cable Drive Capability
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 29
Page 30
XLR Output Pad Jumpers
Four jumpers on four 6-pin headers (P8, P9,
P10, and P11) allow selection of the output
level at the XLR jacks. The jumpers are
properly configured if a normal playback level
is achieved when the VOLUME control is set
above the 11 o'clock position.
automatically mutes the MAIN outputs. In
most cases it is convenient to have one jack
that mutes the outputs and one that does not
mute the outputs. If your requirements are
different the HEADPHONE SWITCHES can
be enabled or defeated.
Headphone Switch Configuration
One pair of 6-pin headers control the
attenuation at each XLR jack as follows:
0 dB - (Attenuator disabled) – (Jumper
plug between pins 1 and 2 of each
header) - Factory Default
-10 dB – (Jumper plug between pins 3
and 4 of each header)
-20 dB – (Jumper plug between pins 5
and 6 of each header)
The HEADPHONE SWITCH on the left-hand
headphone jack is enabled by placing a
jumper across the bottom two pins of P1 (on
the back of the faceplate circuit board), as
shown in Figure 2.
The HEADPHONE SWITCH on the righthand headphone jack can be enabled by
adding a jumper across the top two pins of
P1. A spare jumper is supplied with the
DAC2 DX for use at this location.
No Jumpers - Both switches disabled
Top Jumper Only - Right-hand switch
enabled
Bottom Jumper Only - Left-hand
switch enabled (factory default)
Top and Bottom Jumpers - Both
switches enabled
Jumper(s) rotated vertically - Storage
of unused jumper(s)
Unused jumper(s) may be stored vertically on
either pair of pins.
Figure 1 - Attenuators set to -0 dB
Headphone Switch Configuration
Both headphone jacks are equipped with
switches that can mute the MAIN outputs.
The AUX outputs are not muted by the
headphone switches. The switches can be
enabled by placing jumpers on header P1 (on
the back side of the faceplate). By default,
the mute switch is enabled on the left-hand
jack and disabled on the right-hand jack. In
this default configuration the left-hand jack
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 30
Figure 2 - Left-Hand Headphone Switch
Enabled (Factory Default)
Page 31
Headphone Amplifier Gain
The gain range of the HPA2™ can be set
using jumpers JP3 and JP4:
Gain = 0 dB - see Figure 3
Gain = -10 dB - see Figure 4
(Factory Default)
Gain = -20 dB - see Figure 5
The jumpers change the gain of the HPA2™
headphone amplifier without changing the
output impedance. This keeps the output
impedance of the HPA2™ constant and very
near 0 Ohms. External attenuators should
never be inserted after a headphone amplifier
as this would change the output impedance
and alter the frequency response of the
headphones.
Proper gain settings are important for
maximizing the SNR of the headphone
monitoring system. With proper settings, the
full performance of the DAC2 DX can be
delivered to the headphones for critical
monitoring tasks and for maximum musical
enjoyment.
Tip: When the headphone gain jumpers are
set properly, a normal listening level will be
achieved at a VOLUME control setting above
the 11 o'clock position.
Tip: If a normal listening level is achieved
below an 11 o’clock VOLUME setting, the
headphone gain is too high, and the gain
should be decreased.
Tip: If the level is too low at the maximum
VOLUME setting, the headphone gain is too
low, and the gain should be increased.
Figure 3 - HPA2™ Gain is 0 dB
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 31
Figure 4 - HPA2™ Gain is -10 dB
(Default)
Page 32
By default, D5 functions as a digital input and
the jumpers are set according to Figure 7.
Figure 6 – Digital PASS-THROUGH
Enabled
Figure 5 - HPA2™ Gain is -20 dB
Digital PASS-THROUGH Function
The digital PASS-THROUGH function can be
enabled by moving both P14 jumpers toward
the faceplate shown in Figure 6. Once the
jumpers are moved into the position shown in
Figure 6, D5 is configured as a digital audio
output. When the PASS-THROUGH function
is enabled, D5 cannot be selected as an
input. Any other selected digital input will be
routed to both the internal D/A converter and
to output D5. The digital output at D5 is
buffered, but is not processed. Many digital
audio formats can be passed through to D5
(even when these formats cannot be decoded
by the DAC2 DX).
Figure 7 - Digital PASS-THROUGH
Disabled (Factory Default)
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 32
Page 33
Calibration Settings
1 2 3 4 5 6 7 8 9
10
:
:
:
:
:
:
|
|
|
:
The factory default calibrated output levels are +24 dBu at 0 dBFS on the XLR outputs and 2 V
RMS at 0 dBFS on the unbalanced outputs. This calibration is activated when the MAIN or AUX
busses are placed in CALIBRATED mode. It is also activated on the MAIN bus when the
COMPATIBILITY mode is turned on.
If you wish to change the calibration, you will need to remove or install jumpers on header P6.
There are 10 pairs of pins on P6 that provide 10 jumper positions. Only use positions 7, 8 and 9!
The factory default calibration is selected when all three jumpers are installed, or all three jumpers
removed.
Caution: Do not install jumpers in positions 1, 2, 3, 4, 5, 6 or 10!
The chart and photo below show P6 with jumpers installed in the factory-default positions (7, 8,
and 9). The P6 legend is located near jumper position 1 (see photo).
P6
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 33
Page 34
Calibration Settings (continued)
1 2 3 4 5 6 7 8 9
10
XLR
Level
(dBu)
RCA
Level
(Vrms)
: : : : : : : : :
:
+24
2.00
: : : : : : : : |
:
+20
1.26
: : : : : : : | :
:
+21
1.42
: : : : : : : | |
:
+22
1.59
: : : : : : | : :
:
+23
1.78
: : : : : : | : |
:
+26
2.52
: : : : : : | | :
:
+28
3.17
: : : : : : | | |
:
+24
2.00
When header P6 is viewed front the front of the unit, position 1 is on the far left and position 10 is
on the right. Count the pins starting from the left side of the header. Position 7 is the 7th pair of
pins. Position 8 is the 8th pair of pins. Position 9 is the 9th pair of pins. Do not install jumpers on
any other pins on this header!
Use the following chart to set the P6 jumpers to the desired calibration level:
P6
+28 dBu at 0 dBFS is not recommended due to a loss of digital headroom in the ESS DAC chip.
Intersample peaks may clip.
Tip: The factory default setting can be obtained by installing all three jumpers or by removing all
three jumpers.
Tip: The factory default setting is recommended when using the LA4 or HPA4 as a volume control.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 34
Page 35
Rack Mounting Options
The DAC2 DX is available with or without rackmount ears. Either version can be rack mounted
with the appropriate accessories. There are several accessories available for rack mounting a DAC2
DX:
Connector Block - Joins two ½-wide Benchmark products when both have rackmount-type
faceplates. It can also join a rackmount DAC2 DX directly to a blank plate (no tray
required).
Premium ½-Wide Blank Panel - Fills one side of the rack tray, or mounts directly to a
rackmount DAC2 DX. Panel is 1/4" brushed aluminum with a durable clear-anodized finish.
This premium panel is styled to match the silver rackmount DAC2 DX, and includes a large
engraved Benchmark logo.
Black ½-Wide Blank Panel - Fills one side of the rack tray, or mounts directly to a
rackmount DAC2 DX. Panel is 1/8" brushed aluminum with a durable black-anodized finish.
Universal Rack Adapter Tray - Mounts two ½-wide Benchmark products with any
combination of rackmount and non-rackmount faceplates.
Call us, contact your dealer, or visit http://BenchmarkMedia.com to purchase accessories for
your DAC2 DX.
Rack-Mount Version of the DAC2 DX
Connector Block
The connector block joins two ½-wide Benchmark products with rackmount type faceplates. The joined units fill a standard 19 inch wide 1-RU
rack space. The connector block can also join a single ½-wide Benchmark
product to a Benchmark ½-wide blank panel.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 35
Page 36
Premium ½-Wide Blank Rack Panel
This premium ¼" thick blank panel matches the finish on the silver rackmount version of the DAC2
DX and features an engraved Benchmark logo. It can also be used to cover an unused slot in the
Universal Rack Adapter Tray.
Black ½-Wide Rack Panel
This ⅛" thick blank panel matches the finish on the black non-rackmount version of the DAC2 DX.
This panel can be used to cover an unused slot in the Universal Rack Adapter Tray. It can also
be mounted directly to a rackmount version of the DAC2 DX.
Universal Rack Adapter Tray
The Universal Rack Adapter Tray is a tray that mounts up to two ½-wide Benchmark products in
a standard 19 inch wide 1-RU rack space. The tray accepts any combination of ½-wide Benchmark
products (with or without rack-mount type faceplates). The tray is not necessary if both units are
equipped with rack ears.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 36
Page 37
Rack Mounting Example
Blank Plate and Connector Block:
The Connector Block creates a rigid connection:
Ready to mount in a standard 19" rack:
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 37
Page 38
DAC1 and DAC2 Family
History
The pristine audio performance of the awardwinning DAC1 made it the ‘Benchmark’ of
stand-alone D/A converters. The DAC1 USB,
DAC1 PRE , and DAC1 HDR added many
features to the basic DAC1 platform.
Benchmark converters are in use in many of
the world's top studios.
Three coaxial digital inputs
Three Headphone Gain Ranges
LM4562/LME49860 opamps throughout
Premium bulkhead-mounted RCA
connectors
In order to provide room for the analog inputs,
we removed the XLR digital input and replaced
it with two additional coaxial digital inputs.
DAC1 HDR
The following is a brief overview of the various
Benchmark DAC1 and DAC2 models:
DAC1 Series
DAC1
Benchmark's original DAC1 converter.
The DAC1 features included:
Three digital inputs
XLR outputs with passive pads
RCA outputs
Analog volume control
HPA2™ headphone amplifier
UltraLock™ jitter-attenuation system
DAC1 USB
The DAC1 USB introduced these
improvements:
AdvancedUSB™ computer input
Mute switch on the left headphone jack
Two headphone gain ranges
High-current LM4562/LME49860 output
stages - designed to drive difficult loads
Lower output impedances
Benchmark's AdvancedUSB™ computer input
was the first USB audio interface to support 96
kHz audio without the need to install special
drivers.
DAC1 PRE
The DAC1 PRE added these improvements:
The DAC1 HDR added:
IR Remote Control
HDR-VC™ (high dynamic range
volume control).
The HDR-VC™ features a custom-made,
motor-driven Alps potentiometer. The motordriven control provides the audio performance
of a manual control while adding the
convenience of remote control.
DAC2 Series
DAC2 HGC
The DAC2 HGC maintains the familiar ½-wide
DAC1 form factor, but the entire product was
redesigned from the ground up.
The DAC2 HGC features:
Four 32-bit converters per channel
Native 24-bit/192kHz PCM conversion
Native 64X DSD conversion
High-headroom digital processing
UltraLock2™ jitter attenuation
Multi-mode asynchronous USB audio
input
Sample rate and word length displays
Polarity control
Home theater bypass
Digital pass-through
Bi-directional 12V trigger
Two stereo analog inputs
Three stereo analog outputs
Two optical inputs
High-efficiency low-noise power
supplies
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 38
Page 39
DAC2 L
The DAC2 L is identical to the DAC2 HGC
except that the DAC2 L has no headphone
amplifier.
DAC2 D
The DAC2 D is identical to the DAC2 HGC
except that the DAC2 D has no analog inputs
and no 12V trigger.
DAC2 DX
The DAC2 DX replaced the DAC2 D. The new
model added an XLR digital input and the 12V
trigger. It also added a second output bus so
that one set of outputs could be placed in
calibrated mode while the other was controlled
by the volume knob.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 39
Page 40
Benchmark Technologies
Also, if the pot is manually overridden, it will
not damage the motor.
Hybrid Gain Control™
HGC™ is Benchmark's unique Hybrid Gain
Control™ system. The DAC2 combines active
analog gain control, passive low-impedance
attenuators, a 32-bit digital gain control, and
a servo-driven volume control.
All inputs are controlled by the rotary volume
control. This volume control moves in
response to commands from the remote
control. Analog inputs (included on DAC2
HGC and DAC2 L models) are never
converted to digital. On all DAC2 models,
digital inputs never pass through an analog
potentiometer. Digital inputs are precisely
controlled in the 32-bit DSP system. The DSP
system preserves precise L/R balance, and
precise stereo imaging, while avoiding any
source of noise and distortion.
Benchmark's unique passive output
attenuators provide distortion-free gain
reduction without reducing the dynamic range
of the converter. The attenuators optimize the
gain staging between the DAC2 and the
power amplifier. This optimization is
absolutely essential for maximizing the
dynamic range of the entire playback system.
Much of the success of the DAC1 and DAC2
converters can be attributed to the passive
output attenuators. Musical details can be
obscured by system noise whenever a
preamplifier and power amplifier are
improperly matched. The HGC™ system in
your DAC2 will make full use of your power
amplifier's dynamic range. Experience newly
revealed details in your favorite recordings.
The front-panel volume control is a servodriven gain control built around a custommade Alps potentiometer. The custom Alps
pot is equipped with a remote-controllable
motor drive.
This potentiometer is equipped with a clutch
which prevents damage from overriding the
motor drive. If the pot is driven beyond the
end of its range, it will not damage the motor.
Native DSD Conversion
The digital coaxial inputs and the USB Audio
2.0 input on the DAC2 support native DSD
conversion. DoP 1.1 DSD encapsulation is
automatically detected on all digital inputs.
The system seamlessly switches to native
DSD conversion when DoP is detected. DoP
1.1 DSD encapsulation is supported by many
media players. DSD downloads are now
available from several sources.
High-Headroom DSP
All of the digital processing in the DAC2 is
designed with a headroom of 3.5 dB above 0
dBFS. A sinusoid that just reaches the
maximum positive and negative digital codes
has a level of 0 dBFS. If the peaks of the
sinusoid occur between samples, higher
signals can be captured without clipping. For
a pure tone, the maximum intersample peak
that can be represented by a PCM system is
+3.01 dBFS (see Figure 8).
Benchmark's high-headroom DSP can handle
intersample peaks without overloading or
clipping. Intersample peaks are cleanly
rendered by the DAC2 and are delivered to
the analog outputs without clipping or
distortion (see Figure 10). Very few D/A
converters can make this claim!
In most D/A conversion systems, intersample
peaks cause overloading of the upsampling
interpolators and digital filters that are found
in all sigma-delta converters (see Figure 9).
When overloads occur, bursts of nonharmonic distortion are produced. These
bursts of high-frequency distortion may occur
many times per second and may add a false
brightness and harshness to the sound. This
defect impacts PCM formats but does not
impact 1-bit DSD formats. The absence of
intersample clipping may explain some
people's preference for DSD. The DAC2
delivers clean PCM conversion that meets or
exceeds the clarity of DSD.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 40
Page 41
-1.5
-0.5
0.5
1.5
Intersample Overs
(1 = Maximum Digital Code)
Analog
Audio
Digital
Samples
-1.5
-0.5
0.5
1.5
Conventional Interpolation
(Intersample Overs are Clipped)
Analog
Audio
Digital
Samples
-1.5
-0.5
0.5
1.5
High-Headroom Interpolation
(Intersample Overs are Not Clipped)
Analog
Audio
Digital
Samples
Figure 8 - Intersample Over at +3.01 dB
Intersample overs are common in low sample
rate (44.1 kHz and 48 kHz) commercial
releases. Due to the mathematics and the
bandwidth of typical input signals,
intersample overs are less of a problem in
high sample rate recordings. The reason for
this is that the worst-case (+3.01 dB)
intersample overs occurs for pure tones that
are exactly 1/4 of the sample rate (see
Figure 8). At the 44.1 kHz CD sample rate,
the worst case occurs at 11.025 kHz. It turns
out that many recordings have substantial
peaks near this frequency. In contrast, at a
sample rate of 88.2 kHz, the worst-case
intersample overs occur at a frequency of
22.1 kHz where most musical sources have
insufficient energy to produce significant
intersample overs. The 88.2 kHz sample rate
is still susceptible to intersample overs, but
the magnitude of the worst-case overs tends
to be much lower. For example, at 1/8 of the
sample rate (11.025 kHz), the maximum
intersample peak is about +0.66 dB instead
of the 3.01 dB worst case at a sample rate of
44.1 kHz.
The biggest advantage of higher sample rates
may be the immunity to intersample overs. If
higher sample rates sound better, this
difference may be entirely due to the absence
of DSP overloads caused by intersample
overs. Benchmark's high-headroom DSP
(Figure 10) renders low sample rates with
the clarity and detail normally associated with
high sample rates.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 41
Figure 9 - Clipped Intersample Overs
PCM systems can accurately capture peaks
that exceed 0 dBFS, but these peaks will
overload the oversampling interpolators in
most delta-sigma D/A converters. The
solution is not to eliminate the interpolation
process; the solution is to build interpolators
with more headroom.
Figure 10 - High-Headroom Interpolation
The interpolation process is absolutely
necessary to achieve 24-bit state-of-the art
conversion performance. Unfortunately, most
interpolators clip! This clipping produces
distortion products that are non-harmonic and
non-musical. We believe these broadband
distortion products often add a harshness or
false high-frequency brightness to digital
reproduction. Benchmark DAC2 converters
have high-headroom non-clipping
interpolators. We believe these interpolators
provide groundbreaking improvements to
digital to analog conversion.
Page 42
32-bit ESS SABRE D/A System
Eight balanced 32-bit D/A converters deliver
audio to Benchmark's low-impedance current
to voltage converters. Two converters drive
the two AUX output channels. The remaining
six converters drive the two MAIN output
channels. The 4:1 redundancy on the MAIN
outputs reduces noise by about 4.8 dB. This
redundancy also reduces the THD. The
conversion system at the core of the DAC2 is
as good as it gets. The analog circuits that
follow the D/A converter are carefully
designed. Benchmark has leveraged its long
history of building reference analog audio
equipment to create an outstanding output
stage.
Diagnostic Displays
Ever wonder why that 192 kHz 24-bit
download on your computer just doesn't
sound right? Your media player or computer
may be downsampling to 44.1 kHz and/or
truncating to 16-bits. Many media players and
computer operating systems apply poorquality sample rate conversion and/or
truncation. Fortunately these problems can be
eliminated with the selection of a good
frequency-agile media player.
Many disk players also downsample all
sources to 44.1/16. This processing can do
significant damage to the audio quality.
The sample-rate and word-length displays on
the DAC2 confirm the proper operation of
your disk player, media player, and computer.
Bi-Directional 12 Volt Trigger
Benchmark has re-invented the 12 volt
trigger. The trigger connection on the DAC2
can be used as an input or output or both,
and is compatible with any common 12 volt
trigger input or output. The trigger can be
used to turn a power amplifier on or off
automatically. The DAC2 will also respond to
a 12 volt trigger and follow the actions of
another audio component.
Benchmark components can communicate bidirectionally on the trigger I/O ports. This
bidirectional communication provides greater
flexibility. In a given system, the power
button on any Benchmark device can be used
to start or stop the entire audio system in a
sequenced manner.
Distributed Power Regulation
To achieve the lowest possible noise, the
DAC2 uses distributed power supply
regulation. There are 20 voltage regulators in
the DAC2. Each critical subsystem has at
least one dedicated low-noise voltage
regulator.
We have created two discrete ultra low-noise
regulators for the ES9018 D/A converter. We
use separate regulators for the left and right
channels. This Benchmark exclusive feature
improves the noise and THD performance of
the already-outstanding ES9018 converter
chip.
HPA2™ Headphone Amplifier
The DAC2 headphone output is driven by
Benchmark’s signature HPA2™ headphone
power amplifier. This high-current, highoutput amplifier has an output impedance
that is nearly 0 Ohms. It is designed to drive
loads as low as 30 Ohms without any increase
in distortion. It also has sufficient amplitude
to drive low-sensitivity 600-Ohm headphones.
The HPA2™ includes current-limiting circuits
that fully protect against damage from short
circuits. This is important because the right
channel of a headphone amplifier will
experience a short whenever a mono phone
plug is inserted into the stereo headphone
jack. Shorts may also occur when a plug is
partially inserted.
"0-Ohm" Output Impedance
Most headphone amplifiers use series
resistors to maintain stability and protect
against short-circuit conditions. These
resistors are usually at least 30 Ohms, and
have a negative impact on performance.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 42
Page 43
A headphone amplifier with series resistors
may measure very well on a test bench when
driving resistive loads. However, the same
amplifier will measure very poorly when
driving a headphone load. Unfortunately,
most manufacturers do not measure or
specify headphone amplifier performance
when loaded with real headphones. The
measurements use ideal resistive loads. Our
measurements show that headphones do not
behave like resistive loads.
Headphone Performance
In our tests we have measured substantial
distortion across resistors that are wired in
series with headphones. We have conducted
measurements with a variety of headphones.
In general, distortion increases as headphone
impedance decreases. This distortion can be
eliminated with a properly designed "0-Ohm"
headphone amplifier.
The performance of the HPA2™ does not
change when headphones are driven. THD+N
measurements for no-load, 30-Ohm resistive
loads, 30-Ohm headphone loads, and 600Ohm headphone loads are virtually identical.
The HPA2™ will substantially improve the
sound of 30 and 60-Ohm headphones. It will
make very noticeable improvements with
600-Ohm headphones.
Differential Amplifiers
Differential amplifiers remove common-mode
distortion components from the D/A converter
outputs. This feature is critical for achieving
low-distortion in down-stream devices.
Benchmark addresses common-mode
distortion so that it will not cause distortion in
power amplifiers and other connected
devices. Common-mode distortion can cause
audible distortion while escaping the scrutiny
of an audio analyzer. The balanced and
unbalanced outputs on the DAC2 deliver very
similar performance.
balanced signal with high common-mode
distortion can measure just fine when feeding
a precisely balanced input on a high-quality
audio analyzer. However, any imbalance in a
downstream device will expose the commonmode distortion.
Jitter-Immune UltraLock2™
Benchmark's UltraLock2™ clock system is
featured in the DAC2. The DSP processing is
32-bits, DSP headroom is 3.5 dB, sample rate
is 211 kHz, and jitter-induced distortion and
noise is at least 160 dB below the level of the
music - well below the threshold of hearing.
Benchmark's UltraLock2™ system eliminates
all audible jitter artifacts while achieving
instantaneous locking.
The Importance of Eliminating Jitter
Accurate 24-bit audio conversion requires a
very low-jitter conversion clock. Jitter can
very easily turn a 24-bit converter into a 16bit converter (or worse). There is no point in
buying a 24-bit converter if clock jitter has
not been adequately addressed.
Jitter is present on every digital audio
interface. This type of jitter is known as
‘interface jitter’ and it is present even in the
most carefully designed audio systems.
Interface jitter accumulates as digital signals
travel down a cable from one digital device to
the next. If we measure interface jitter in a
typical system we will find that it is 10 to
10,000 times higher than the maximum
allowable level for accurate 24-bit conversion.
Fortunately, interface jitter has absolutely no
effect on the audio unless it influences the
conversion clock in an analog-to-digital
converter (A/D), the conversion clock in a
digital-to-analog converter (D/A), or the rate
estimator in an asynchronous sample rate
converter (ASRC).
Many D/A converters omit the differential
amplifiers after the converters. Specifications
usually ignore common-mode distortion. A
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 43
Page 44
Many converters use a single-stage Phase
Lock Loop (PLL) circuit to derive their
conversion clocks from AES/EBU, wordclock,
or superclock reference signals. Single-stage
PLL circuits provide some jitter attenuation
above 5 kHz but none below 5 kHz.
Unfortunately, digital audio signals often have
their strongest jitter components at 2 kHz.
Consequently, these converters can achieve
their rated performance only when driven
from very low jitter sources and through very
short cables. It is highly unlikely that any
converter with a single-stage PLL can achieve
better than 16 bits of performance in a typical
installation. Specified performance may be
severely degraded in most installations.
Better converters often use a two-stage PLL
circuit to filter out more of the interface jitter.
In theory, a two-stage PLL can remove
enough of the jitter to achieve accurate 24-bit
conversion (and some do). However, not all
two-stage PLL circuits are created equal.
Many two-stage PLLs do not remove enough
of the low-frequency jitter. In addition, twostage PLL circuits often require several
seconds to lock to an incoming signal. Twostage PLL circuits may fail to lock when jitter
is too high, or when the reference sample
frequency has drifted.
UltraLock™ converters exceed the jitter
attenuation performance of two-stage PLL
converters while achieving near instantaneous
lock time. They are free from the slow-lock
and no-lock problems that can plague twostage PLL designs. UltraLock™ converters
have extremely high immunity to interface
jitter under all operating conditions.
The UltraLock™ system is so effective that
no jitter-induced artifacts could be detected
using an Audio Precision System 2 Cascade
test set while the inputs to the DAC2 were
exposed to high levels of interface jitter. The
measurement limits included the ability to
detect artifacts as low as –144 dBFS, but
none could be detected, even while applying
jitter amplitudes as high as 12.75 UI, over a
frequency range of 2 Hz to 200 kHz. Any
AES/EBU signal that can be decoded by the
AES/EBU receiver in the DAC2 will be
reproduced without the addition of any
measurable jitter artifacts.
Benchmark’s UltraLock™ technology
eliminates jitter-induced performance
problems. UltraLock™ technology isolates
the conversion clock from the digital audio
interface clock. Jitter on a D/A digital audio
input, or an A/D reference input can never
have any measurable effect on the conversion
clock of an UltraLock™ converter. In an
UltraLock™ converter, the conversion clock
is never phase-locked to a reference clock.
Instead the converter oversampling-ratio is
varied with extremely high precision to
achieve the proper phase relationship to the
reference clock. The clock isolation of the
UltraLock™ system ensures that interface
jitter can never degrade the quality of the
audio conversion. Specified performance is
consistent and repeatable in any installation
with cables of any quality level!
How does conversion clock jitter degrade
converter performance?
Problem #1: Jitter phase-modulates the
audio signal. This modulation creates
sidebands (unwanted tones) above and below
every tone in the audio signal. Worse yet,
these sidebands are often widely separated
from the tones in the original signal.
Jitter-induced sidebands are not musical in
nature because they are not harmonically
related to the original audio. Furthermore,
these sidebands are poorly masked (easy to
hear) because they can be widely separated
above and below the frequencies of the
original audio tones. In many ways, jitter
induced distortion resembles intermodulation
distortion (IMD). Like IMD, jitter induced
distortion is much more audible than
harmonic distortion, and more audible than
THD measurements would suggest.
Jitter creates ‘new audio’ that is not
harmonically related to the original audio
signal. This ‘new audio’ is unexpected and
unwanted. It can cause a loss of imaging, and
can add a low and mid frequency ‘muddiness’
that was not in the original audio.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 44
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Jitter-induced sidebands can be measured
using an FFT analyzer while the converter
plays a pure high-amplitude tone. We
typically use a full-scale 10 kHz test tone to
test for the presence of jitter-induced side
bands (Graph 15 - JITTER TOLERANCE
FFT). This FFT shows that the DAC2 is free
from any jitter-induced sidebands to a
measurement limit of about -144 dB relative
to the level of the test tone. The graph plots
the output spectrum of the DAC2 when
exposed to 31 different jitter frequencies
ranging from 100 Hz to 100 kHz. All 31
output spectra are identical and are free from
any signs of jitter-induced distortion.
Problem #2: Jitter can severely degrade the
anti-alias filters in an oversampling converter.
This is a little known but easily measurable
effect. Most audio converters operate at high
oversampling ratios. This allows the use of
high-performance digital anti-alias filters in
place of the relatively poor performing analog
anti-alias filters. In theory, digital anti-alias
filters can have extremely sharp cutoff
characteristics, and very few negative effects
on the in-band audio signal. Digital anti-alias
filters are usually designed to achieve at least
100 dB of stop-band attenuation. But, digital
filters are designed using the mathematical
assumption that the time interval between
samples is a constant. Unfortunately, sample
clock jitter in an A/D or D/A varies the
effective time interval between samples. This
variation alters the performance of these
carefully designed filters. Small amounts of
jitter can severely degrade stop-band
performance, and can render these filters
useless for preventing aliasing.
The obvious function of a digital anti-alias
filter is the removal of audio tones that are
too high in frequency to be represented at the
selected sample rate. The not-so-obvious
function is the removal of high-frequency
signals that originate inside the converter
box, or even originate inside the converter IC.
These high-frequency signals are a result of
crosstalk between digital and analog signals,
and may have high amplitudes in a poorly
designed system. Under ideal (low jitter)
conditions, the digital anti-alias filter may
remove most of this unwanted noise before it
can alias down into lower (audio) frequencies.
These crosstalk problems may not become
obvious until jitter is present.
Stop-band attenuation can be measured very
easily by sweeping a test tone between 24
kHz and at least 200 kHz while monitoring the
output of the converter.
Put UltraLock™ converters to the test:
We encourage our customers to perform the
above tests on UltraLock™ converters (or let
your ears be the judge). There will be
absolutely no change in performance as jitter
is added to any digital input on an
UltraLock™ converter. Try the same tests on
any converter using conventional single or
two-stage PLL circuits. Tests should be
performed with varying levels of jitter and
with varying jitter frequencies. The results will
be very enlightening. Jitter related problems
have audible (and measurable) effects on A/D
and D/A devices. Practitioners of Digital Audio
need to understand these effects.
Is it possible to eliminate all of the
effects of jitter in an entire digital audio
system?
Interface jitter will accumulate throughout
even the most carefully designed digital audio
system. Fortunately, interface jitter can
only degrade digital audio if it affects the
sampling circuit in an analog-to-digital or
digital-to-analog converter. Any attempt to
cure jitter outside of an A/D or D/A will prove
expensive and, at best, will only partially
reduce jitter-induced artifacts. Dedicated
clock signals (word clock, and super clock,
etc.) are often distributed to A/D converters
and D/A converters in an attempt to reduce
jitter. Again, these are only partial solutions
because jitter even accumulates in these
clock distribution systems. Furthermore, a
poor quality master clock generator can
degrade the performance of the entire system
(if converter performance is dependent upon
reference clock quality). Jitter-free A/D and
D/A converters are the only true insurance
against the ill effects of jitter.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 45
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UltraLock™ converters are jitter-immune
under all operating conditions (they will never
add audible jitter-induced artifacts to an
audio signal).
available, make sure that there are no other
devices sharing the USB hub that services the
port. When possible, connect the DAC2 to a
port that supports USB 2.0 or higher.
What UltraLock™ converters cannot do:
UltraLock™ converters cannot undo damage
that has already been done. If an A/D with a
jitter problem was used to create a digital
audio signal, then there is nothing that can be
done to remove the jitter-induced distortion
that happened inside the A/D converter.
Jitter-induced sidebands are extremely
complex and cannot be removed with any
existing audio device. Therefore, it is very
important to attack jitter at both ends of the
audio chain. The DAC2 is a great start, as it
will allow accurate assessment of various A/D
converters. It is impossible to audibly
evaluate A/D performance without a good
D/A. The consistent performance delivered by
the DAC2 eliminates one major variable jitter.
Multi-Mode Asynchronous USB
Audio
Plug it in and Start Listening…
Immediately
Benchmark's Advanced USB Audio system
supports the industry standard USB Audio
1.1 and USB Audio 2.0 protocols. These
audio protocols should not be confused with
USB port speeds. The USB Audio 1.1
protocol requires at least a USB 1.0 (Full
Speed) port. USB Audio 2.0 requires at least
a USB 2.0 (High Speed) port.
Tip: The USB Audio 2.0 protocol is required
for sample rates above 96 kHz. This protocol
will not run on USB 1.0 ports. When possible,
connect the DAC2 to a port that supports
USB 2.0 or higher.
Asynchronous USB
In all modes the USB communications are
asynchronous. An ultra low jitter conversion
clock is generated inside the DAC2. The
asynchronous USB interface pulls data from
the computer without using computergenerated clocks. The D/A conversion in the
DAC2 is completely isolated by the
asynchronous USB interface and by the
UltraLock2™ jitter-attenuation system.
The DAC2 has a low-jitter master clock which
controls the transfer of audio data from the
computer to the USB sub-system. The
computer asynchronously transfers audio data
to a buffer in the DAC2. The contents of the
buffer are then asynchronously transferred to
the D/A conversion sub-system. This second
asynchronous transfer eliminates any traces
of jitter that accumulate as the data is
transferred between the USB and conversion
subsystems. No traces of jitter-induced
distortion are detectable at our measurement
limits (about -144 dBFS). This truly
represents the state-of-the art. Enjoy the
convenience of computer playback without
compromise.
Benchmark's USB Audio 1.1 and USB Audio
2.0 modes are frequency agile. This means
that the sample rate is controlled by the
computer. The DAC2 will follow sample rate
changes initiated by the computer and/or the
media playback software.
Tip: The USB Audio 1.1 protocol will run on
any USB port, but if it is run on a USB 1.0
(Full Speed) port, it will require all of the
available bandwidth to support 96 kHz sample
rates. If a USB 1.0 port is the fastest port
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 46
The Asynchronous USB system supports USB
Audio 2.0 for high-resolution 192kHz, and
DSD playback. No drivers are required for
MAC operating systems. An easy-to-install
driver adds 192 kHz and DSD capabilities to
Windows operating systems.
The asynchronous driverless USB Audio 1.1
mode supports sample rates up to 96 kHz.
This USB mode can be selected from the front
panel or from the remote control.
Page 47
The driverless USB Audio 1.1 mode allows
quick plug-and-play connections to Windows,
MAC, iOS, and Linux operating systems
without installing drivers. Just plug in the
USB, and the DAC2 becomes an available
audio device. In many cases, audio will
automatically be routed to the newly
connected device. If not, it can be selected as
the current or default playback device.
The industry-standard USB Audio Mode 2.0
mode is natively supported by Windows
operating systems starting with Windows 10.
A driver is required for older Windows
operating systems. The driver supports
Windows XP, Vista, or 7, and 8. This driver is
required for DSD and sample rates above 96
kHz when using these older Windows
systems.
The USB subsystem is computer powered
(through the USB cord) and it remains active
when the DAC2 is powered down. This
feature prevents interruptions to the
computer playback operations and eliminates
the need to reconfigure the computer every
time the converter is turned on.
The Windows USB Audio 2.0 driver is
available at:
BenchmarkMedia.com/drivers
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 47
Page 48
USB Driver Installation
Required for Windows operating systems prior to Windows 10 only!
Note: The DAC2 driver is available for download at: BenchmarkMedia.com/drivers
Note: To provide full backward and forward compatibility, the DAC3 uses the DAC2 USB drivers.
This prevents the need to install two different sets of drivers. Please note that the DAC3 USB input
will be identified as "Benchmark DAC2" in your computer control panels. This is intentional.
Before you install the driver, make sure the USB cable is unplugged.
1. In the DAC2 Driver folder, double click “setup.exe.”
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 48
Page 49
2. A welcome screen will pop-up. Click “Next.”
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 49
Page 50
3. When you see the following screen, turn on the DAC2, plug in the USB cable, and select the
USB input on the DAC2. By default, the DAC2 is shipped in USB Audio 1.0 mode. Do not
proceed to the next step until the USB Audio 2.0 mode has been enabled. You can enable
the USB Audio 2.0 mode using one of the following two methods:
METHOD 1 - REMOTE CONTROL: Using your remote control, press and hold USB
button for 10 seconds (the 4X light should flash once). If the 2X light flashes instead
of the 4X light, repeat this step.
METHOD 2 - FRONT PANEL: From the front panel, select the USB input and then
hold the lower INPUT button for 10 seconds (the 4X light should flash once). If the
2X light flashes instead of the 4X light, repeat this step.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 50
Page 51
4. You will now be prompted to select a location to install the driver. It will default to your
Program Files folder. If you wish to install it another location, you can change the location.
We suggest keeping it in the default location. Click “Install”.
5. When the installation begins you will see the following screen. Please be patient while the
driver installs. Installation may require several minutes.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 51
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6. When the installation finishes a message at the top will say “Installation Complete.” Click
“Next” to continue.
7. Click “Finish.” The Setup will close automatically. This completes the installation process.
You can now enjoy music over the USB Audio 2.0 connection at sample rates up to 192
kHz. DSD can also be played in DoP 1.1 format.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 52
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Performance Graphs
Audio Precision
FFT Idle Channel Noise, 0 dBr = 0 dBFS = 23 dBu
DAC2 - FFT Idle Channe l Nois e.at27
ColorSweep Trace Line Style Thick Data Axis Com ment
1 1 Green Solid 4 Fft.Ch.1 Ampl Left
1 2 Red Solid 4 Fft.Ch.2 Ampl Righ t
-160
+0
-140
-120
-100
-80
-60
-40
-20
d
B
r
A
-160
+0
-140
-120
-100
-80
-60
-40
-20
d
B
r
A
0 32k2k 4k 6k 8k 10k 12k 14k 16k 18k 20k 22k 24k 26k 28k 30k
Hz
The following graphs were produced using a DAC2 HGC. The DAC2 DX provides similar
performance.
Graph 1 - FFT Idle Channel Noise
The extraordinary performance of the DAC2 is demonstrated by the FFT plot shown above. There
is no sign of any AC hum, there are no idle tones, and there are no spurious tones detected at a
measurement limit of -160 dBFS.
The rise at 0 Hz is normal in an FFT analysis and is not an indication of noise. This 32k point FFT
analysis uses a Blackman-Harris window with 16x power averaging, and spans a frequency range
of DC to 32 kHz.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 53
Page 54
Audio Precision
FFT Idle Channel Noise - Low Frequency, 0 dBr = 0 dBFS = 23 dBu
DAC2 - FFT Idle Channel Nois e - Low Frequen cy.at27
ColorSweep Trace Line Style Thick Data Axis Com ment Curs or1 Curs or2
1 1 Green Soli d 4 Fft.Ch.1 Ampl Left *-15 6.413 dBr *-157.53 9 dBr
1 2 Red Soli d 4 Fft.Ch.2 Am pl Right -159.813 dBr A -158.700 dBr A
-160
+0
-140
-120
-100
-80
-60
-40
-20
d
B
r
A
-160
+0
-140
-120
-100
-80
-60
-40
-20
-156.413
-157.539
d
B
r
A
25 400 50 75 100 125 150 175 200 225 250 275 300 325 350 375
60.1566 180.626
Hz
dx=120.470 Hz
dy=-1.126 dB
Graph 2 - LOW FREQUENCY FFT - AC LINE-RELATED HUM
The DAC2 shows no evidence of AC line-related hum to a measurement limit of -160 dBFS. The
cursors are placed at 60 Hz and 180 Hz (frequencies where we would expect to see interference
from the 60 Hz AC input. There is absolutely no sign of any AC hum.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 54
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Graph 3 - FFT 10 kHz
Audio Precision
DAC2 - FFT 10 kHz, 0 dBr = 0 dBFS = 23 dBu
DAC2 - FFT 10 kHz.at27
ColorSweep Trace Line Style Thick Data Axis Com ment Curs or1 Cursor2
1 1 Green Solid 4 Fft.Ch.1 Ampl Left *-11 4.636 dBr *-120 .240 dBr
1 2 Red Solid 4 Fft.Ch.2 Ampl Righ t -1 16.765 dBr A -122.816 dBr A
-160
+0
-140
-120
-100
-80
-60
-40
-20
d
B
r
A
-160
+0
-140
-120
-100
-80
-60
-40
-20
-114.636
-120.24
d
B
r
A
0 32k2k 4k 6k 8k 10k 12k 14k 16k 18k 20k 22k 24k 26k 28k 30k
20.0391k 30.0587k
Hz
dx=10.0196 kHz
dy=-5.604 dB
The 10 kHz FFT analysis is an excellent test for detecting sample clock jitter. Jitter will create
sidebands (unwanted tones) above and below the 10 kHz test tone. A jitter frequency of 1 kHz
would create two sideband tones; a lower sideband at 9 kHz, and an upper sideband at 11 kHz.
Similarly, a jitter frequency of 2 kHz would produce sideband tones at 8 kHz and 12 kHz. The
above plot shows no evidence of jitter-induced sidebands to a measurement limit of about -140
dBFS.
The -140 dB measurement limit is due to the SNR limitations of the Audio Precision 2700 test set,
and not the DAC2. Note the very low harmonic distortion; -114 to -116 dB 2nd harmonic (20 kHz),
and -120 to -122 dB 3rd harmonic (30 kHz). Please note that these are almost exactly the same
harmonic distortion levels that occur with a 1 kHz tone (see Graph 4 - FFT 1 kHz). This
demonstrates that the DAC2 analog stages have the high slew rates required to pass highamplitude high-frequency signals without an increase in harmonic distortion.
The rise at 0 Hz is normal in an FFT analysis and is not an indication of noise. This 32k point FFT
analysis uses a Blackman-Harris window with 16x power averaging, and spans a frequency range
of DC to 32 kHz.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 55
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Audio Precision
DAC2 - FFT 1 kHz, 0 dBr = 0 dBFS = 23 dBu
DAC2 - FFT 1 kHz.at27
ColorSweep Trace Line Style Thick Data Axis Com ment Curso r1 Curso r2
1 1 Green Soli d 4 Fft.Ch.1 Am pl Left *-115.268 dBr *-128.290 dBr
1 2 Red Solid 4 Fft.Ch.2 Ampl Right -115.95 4 dBr A -130.429 dBr A
-160
+0
-140
-120
-100
-80
-60
-40
-20
d
B
r
A
-160
+0
-140
-120
-100
-80
-60
-40
-20
-115.268
-128.29
d
B
r
A
0 3.2k200 400 600 800 1k 1.2k 1.4k 1.6k 1.8k 2k 2.2k 2.4k 2.6k 2.8k 3k
2.00391k 2.99961k
Hz
dx=.995695 kHz
dy=-13.022 dB
Graph 4 - FFT 1 kHz
The 1 kHz FFT analysis demonstrates the low harmonic distortion of the DAC2. Second harmonic
distortion (2 kHz) measures about -115 dB, while 3rd harmonic distortion measures -128 to -130
dB.
The rise at 0 Hz is normal in an FFT analysis and is not an indication of noise. This 32k point FFT
analysis uses a Blackman-Harris window with 16x power averaging, and spans a frequency range
of DC to 32 kHz.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 56
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Graph 5 - FREQUENCY RESPONSE
Audio Precision
10/24/12 16:02:03
DAC2 - FREQUENCY RESPONSE
Fs = 96 kHz
DAC2 - Frequency Respo ns e.at27
ColorSweep Trace Line Style Thick Da ta Axis Comm ent Cu rso r1 Curs or2
1 1 Green Soli d 4 Anlr.Level A Left -0.011 dBr A -0.026 dBr A
1 2 Red Solid 4 Anlr.Level B R ight *-0.009 dBr *-0.020 dBr
-10
+1
-9
-8
-7
-6
-5
-4
-3
-2
-1
-0
-0.009-0.02
d
B
r
B
-10
+1
-9
-8
-7
-6
-5
-4
-3
-2
-1
-0
d
B
r
A
5k 45k10k 15k 20k 25k 30k 35k 40k
10.0021 40.4214k
Hz
dx=40.4114 kHz
dy=-0.011 dB
This plot demonstrates the ruler-flat frequency response of the DAC2. Note that the frequency
response measures - 0.01 dB at 10 Hz and -0.02 dB at 40 kHz.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 57
Page 58
Graph 6 - Differential Phase
Audio Precision
DAC2 - Differential Phase
Fs = 96 kHz
DAC2 - Differential Phas e.at27
ColorSweep Tra ce Line Style Thick Da ta Axis Com men t Curso r1 Cursor2
1 1 Green Sol id 4 Anlr.Phas e Left -0.09 deg -0.21 deg
2 1 Red Solid 4 Anlr.Phas e Left *+0.24 deg *+0 .47 deg
-1
+1
-0.8
-0.6
-0.4
-0.2
+0
+0.2
+0.4
+0.6
+0.8
+0.24
+0.47
d
e
g
2.5k 45k5k 7. 5k 10k 12.5k 15k 17.5k 20k 22.5k 25k 27.5k 30k 32.5k 35k 37.5k 40k 42.5k
20.2555k 40.0511k
Hz
dx=19.7956 kHz
dy=+0.23 deg
This plot demonstrates the inter-channel phase accuracy of the DAC2. From this plot, the interchannel phase accuracy is calculated to be +/- 0.17 degrees at 20 kHz, and +/- 0.34 degrees at 40
kHz.
The phase accuracy of the DAC2 is almost the same as the phase accuracy of the Audio Precision
2700 test set. For this reason, the phase error in the AP must be subtracted from the
measurement. The green trace assigns the left channel to channel 1 of the AP, and the right
channel to channel 2 of the AP. The red trace reverses the inputs. The two traces must be
averaged to remove the phase errors of the AP test set.
DAC2 converters are phase-accurate between boxes. Three DAC2 converters can be used as a
group to form a phase-accurate 5.1 surround system. Four DAC2 converters can be combined to
form a 7.1 system. The phase accuracy between any two channels will match the phase accuracy
shown above.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 58
Page 59
Graph 7 - Balanced THD+N vs. Amplitude
Audio Precision
DAC2 - THD+N vs AMPLITUDE AT 1 KHZ (w/20 kHz LPF unweighted)
Balanced Outputs, Relative to 0 dBFS, 0 dBFS = +23 dBu
DAC2 - Balanced THD+N vs AMPLITUDE.at27
ColorSweep Tra ce Line Style Thick Da ta Axis Co mm ent
1 1 Green Sol id 4 Anlr.THD+N Ampl Le ft
1 2 Red Solid 4 Anlr.THD+N Ampl Left
-120
-96
-118
-116
-114
-112
-110
-108
-106
-104
-102
-100
-98
d
B
r
A
-14 -0-13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1
dBFS
This plot demonstrates the very low harmonic distortion produced by the DAC2 at signal levels
ranging from -14 dBFS to 0 dBFS. All variations below -4 dBFS are due to the measurement limits
of the AP 2700 system. The peaks at -13 dBFS are due to an AP 2700 gain range change. In
almost all listening environments, THD will be below the threshold of hearing. The DAC2 is virtually
uncolored by any trace of harmonic distortion.
The DAC2 includes differential amplifiers that remove common-mode distortion components. This
is important, because common-mode distortion is not detected when measuring with the preciselybalanced inputs on the AP 2700 test set. The THD+N measurements on the unbalanced outputs
confirm the effectiveness of the differential amplifiers. Similar results are obtained by measuring
either side of the balanced outputs relative to ground.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 59
Page 60
Graph 8 - Unbalanced THD+N versus Amplitude
Audio Precision
DAC2 - THD+N vs AMPLITUDE AT 1 KHZ (w/20 kHz LPF unweighted)
Unbalanced Outputs, Relative to 0 dBFS, 0 dBFS = +7.2 dBu
DAC2 - Unbalanced THD+N _VS_AMPLITUDE.at27
ColorSweep Trace Li ne Style Thick Data Axis Comm ent
1 1 Green Solid 4 Anlr.THD+N Ampl Le ft
1 2 Red So lid 4 Anlr.THD+N Ampl Left
-120
-95
-119
-118
-117
-116
-115
-114
-113
-112
-111
-110
-109
-108
-107
-106
-105
-104
-103
-102
-101
-100
-99
-98
-97
-96
d
B
r
A
-14 -0-13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1
dBFS
This plot shows the THD+N performance of the unbalanced outputs. Note that the THD+N
performance of the unbalanced outputs approaches that of the balanced outputs. The DAC2
includes differential amplifiers that remove common-mode THD from the balanced outputs of the
SABRE converters. These differential amplifiers give the unbalanced outputs the ability to approach
the performance of the balanced outputs. Please note that the differential amplifiers also eliminate
common-mode distortion on the balanced outputs.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 60
Page 61
Graph 9 - Headphone Amplifier – THD+N versus Amplitude
Audio Precision
DAC2 - THD+N vs AMPLITUDE AT 1 KHZ (w/20 kHz LPF unweighted)
Headphone Outputs, Relative to 0 dBFS, 0 dBFS = +7.2 dBu
DAC2 - HEADPHONE - THD+N_VS_AMPLITUDE.at27
ColorSweep Trace Line Style Thick Data Axis Com men t
1 1 Green Solid 4 Anlr.THD+N Ampl Left
1 2 Red Solid 4 Anlr.THD+N Ampl L eft
-104
-86
-102
-100
-98
-96
-94
-92
-90
-88
d
B
r
A
-14 -0-13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1
dBFS
This plot shows the THD+N performance of the headphone outputs under load. Note that the
THD+N performance of the headphone outputs approaches that of the balanced outputs. The
DAC2 includes Benchmark's HPA2™ headphone amplifier. The HPA2™ has a near 0-Ohm output
impedance which provides outstanding control and damping of the headphone drivers. The HPA2™
has the voltage and current drive necessary to drive a wide variety of headphones.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 61
Page 62
Graph 10 - THD+N vs. FREQUENCY 80 kHz
Audio Precision
DAC2 - THD+N VS FREQ AT 0 dBFS (w/80 kHz LPF
unweighted)
Balanced Outputs
DAC2 - THD+N vs FREQUENCY 80kHZ.at27
-110
-90
-107.5
-105
-102.5
-100
-97.5
-95
-92.5
d
B
20 20k 50 100 200 500 1k 2k 5k 10k
Hz
The analog output stages on the DAC2 have high slew rates and are capable of maintaining low
THD levels at high frequencies even when driven to 0 dBFS. Note that there is almost no rise in
THD+N with frequency, even when operating at maximum output levels.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 62
Page 63
Audio Precision
DAC2 - THD VS FREQ AT 0 dBFS
Balanced Outputs
DAC2 - EVEN AND ODD THD vs FREQUENCY.at27
ColorSwe ep Trace Line Style Thick D ata Axis Com men t Cursor1 Cu rsor2
1 1 Green Solid 4 D istortio n.Ch.1 Harm Sum1 Ra tio Left *-115.210 dB *-11 2.066 dB
1 2 Red So lid 4 Dis tortion.Ch.1 Harm Sum2 Ratio Ri ght -115.165 dB -12 0.544 dB
GREEN = EVEN HARMONIC DISTORTION (2,4,6,8,10,12,14)
RED = ODD HARMONIC DISTORTION (3,5,7,9,11,13,15)
-130
-90
-125
-120
-115
-110
-105
-100
-95
d
B
-130
-90
-125
-120
-115
-110
-105
-100
-95
-115.21
-112.066
d
B
20 10k 50 100 200 500 1k 2k 5k
1.00318k 10k
Hz
dx=8.99682 kHz
dy=+3.144 dB
Graph 11 - EVEN AND ODD THD vs. FREQUENCY
This plot demonstrates that the harmonic distortion of the DAC2 is lower than the THD+N numbers
would suggest. This plot shows THD not THD+N. Even and odd harmonic distortions are plotted
separately. Note that odd harmonics are lower than the more "musical" even harmonics. Both sets
of harmonics are very low in amplitude (-112 dB to -120 dB), and should be entirely inaudible.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 63
Page 64
Audio Precision
DAC2 - THD VS FREQ AT 0 dBFS
- ALL OUTPUTS
DAC2 - THD vs FREQUENCY.at27
ColorSweep Trace Li ne Style Thick Data Axi s Comm ent Source 2 Curs or1
1 2 Bl ue Solid 4 Di stortion .Ch.1 Harm Sum1 Ra tio Left : 1.00000 =Swr.Ch. A+B Input -1 12.557 dB
1 3 C yan Solid 4 Distortion .Ch.2 Harm Sum1 Ra tio Right : 1.00000 =Swr.Ch. A+B Input -1 12.453 dB
2 2 Red Solid 4 Di stortion .Ch.1 Harm Sum1 Ra tio Left : 3.00000 =Swr.Ch. A+B Input -1 13.919 dB
2 3 Magenta Solid 4 Distortion .Ch.2 Harm Sum1 Ra tio Right : 3.00000 =Swr.Ch. A+B Input -113.349 dB
3 2 Green Soli d 4 Di stortion .Ch.1 Harm Sum1 Ra tio Left : 5.00000 =Swr.Ch. A+B Input -1 17.017 dB
3 3 Yellow Soli d 4 Di stortion .Ch.2 Harm Sum1 Ra tio Right : 5.00000 =Swr.Ch. A+B Input * -114.827 dB
1=Balan ced L
2=Balan ced R
3=Unba lanced L
4=Unba lanced R
5=Head phone L
6=Head phone R
-130
-90
-125
-120
-115
-110
-105
-100
-95
-114.827
-106.739
d
B
-130
-90
-125
-120
-115
-110
-105
-100
-95
d
B
20 10k 50 100 200 500 1k 2k 5k
1.00318k 10k
Hz
dx=8.99682 kHz
dy=+8.088 dB
Graph 12 - THD vs. Frequency - All Outputs
This plot demonstrates that all of the analog outputs on the DAC2 have very similar performance
over the entire audio band. The unbalanced outputs, and the headphone outputs, closely match the
performance of the balanced outputs. Like Graph 11, this plot shows THD (not THD+N).
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 64
Page 65
Graph 13 - THD+N versus Sample Rate
Benchmark Media Systems, Inc.
DAC2 - THD+N vs Sample Rate, 1 kHz at 0 dBFS (w/20 kHz LPF unweighted)
Balanced Outputs
DAC2 - THD+N vs Sample Rate.at27
ColorSweep Trace Line Style Thick D ata Axis Comm ent
1 1 Green So lid 4 Anlr.THD+N Ratio Left
1 2 Red Solid 4 Anlr.THD+N Ratio Left
-120
-90
-117.5
-115
-112.5
-110
-107.5
-105
-102.5
-100
-97.5
-95
-92.5
d
B
40k 200k60k 80k 100k 120k 140k 160k 180k
Hz
The THD+N performance of the DAC2 is identical at all Sample Rates.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 65
Page 66
Graph 14 - JITTER TOLERANCE
Audio Precision
DAC2 - INTERFACE JITTER TOLERANCE - Distortion vs Jitter
3.456 kHz Test Tone at 0 dBFS, THD+N 22 to 22 kHz BW
DAC2 - JITTER TOLERANCE.at27
ColorSwee p Trace Line Style Thick Da ta Axis Com me nt
1 1 Green Solid 4 Anlr.THD+N Ratio Left
1 2 Red So lid 4 Dio.Interface Jitter Ri ght
DAC2 THD+N (22-22kHz) (Green Trace) vs. Interface Jitter (Red Trace)
Digital Inpu t = 3.456 kHz Tone at 0 dBFS, Fs = 48 kHz
10m
20
20m
50m
100m
200m
500m
1
2
5
10
U
I
-110
+0
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
d
B
100 90k200 500 1k 2k 5k 10k 20k 50k
Hz
The Audio Engineering Society (AES) has created a jitter tolerance template for testing digital audio
devices. The red curve shows the AES jitter tolerance template. Induced jitter approaches 5 UI at
200 Hz, and is reduced to 0.125 UI above 8 kHz. The green trace shows the THD+N of the DAC2
while being driven with the jitter shown on the red curve. Over the entire range of the AES jitter
tolerance test, the THD+N performance of the DAC2 is unchanged. The DAC2 easily passes the
AES jitter tolerance test without any THD+N performance degradation.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 66
Page 67
Audio Precision
DAC2 - INTERFACE JITTER TOLERANCE FFT
10 kHz Test Tone at 0 dBFS, AES Jitter Tolerance Sweep
-140
+0
-120
-100
-80
-60
-40
-20
d
B
r
A
0 32k 2k 4k 6k 8k 10k 12k 14k 16k 18k 20k 22k 24k 26k 28k 30k
Graph 15 - JITTER TOLERANCE FFT
This plot shows an series of FFTs that were acquired while running the AES jitter tolerance test.
Note that none of the 31 FFTs show any signs of jitter-induced sidebands. Note that the plots are
identical to the plots shown in Graph 3 - FFT 10 kHz. The DAC2 shows no change in performance
when the AES jitter tolerance test is applied to the digital inputs. No jitter-induced sidebands are
visible to a measurement limit that exceeds -140 dBFS.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 67
Page 68
Audio Precision
11/06/12 08:15:12
DAC2 - 11K 12K IMD
DAC2 - IMD 11K 12K.at27
-160
+0
-150
-140
-130
-120
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
d
B
r
A
-160
+0
-150
-140
-130
-120
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
-122.154
-128.885
d
B
r
A
0 20k 2k 4k 6k 8k 10k 12k 14k 16k 18k
1.01761k 10.0196k
Hz
dx=9.00196 kHz
dy=-6.731 dB
Graph 16 - IMD 11k 12K
This plot demonstrates that the DAC2 has very low IMD distortion. The 1 kHz difference frequency
measures -122 dB, and the 10 kHz and 13 kHz products measure about -128 dB. IMD distortion
should be well below audible levels.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 68
Page 69
Specifications
Audio Performance
Fs = 44.1 to 96 kHz, 20 to 20 kHz BW, 1 kHz test tone, 0 dBFS = +24 dBu (unless noted)
SNR – A-Weighted, 0 dBFS = +20 to +29 dBu
126 dB
SNR – Unweighted, 0 dBFS = +20 to +29 dBu
123 dB
THD+N, 1 kHz at 0 dBFS
-109 dBFS, -109 dB, 0.00035%
THD+N, 1 kHz at -1 dBFS
-110 dBFS, -109 dB, 0.00035%
THD+N, 1 kHz at –3 dBFS
-113 dBFS, -109 dB, 0.00035%
THD+N, 20 to 20 kHz test tone at –3 dBFS
-112 dBFS, -108 dB, 0.00040%
Frequency Response at Fs=96 kHz
+0 dB, -0.04 dB (20 to 20 kHz)
-0.04 dB at 10 Hz
-0.04 dB at 20 kHz
-0.04 dB at 40 kHz
-0.7 dB at 45 kHz
Frequency Response at Fs=48 kHz
+0 dB, -0.04 dB (20 to 20 kHz)
-0.04 dB at 10 Hz
-0.04 dB at 20 kHz
Crosstalk
-116 dB at 20 kHz
-130 dB at 1 kHz
-137 dB at 20 Hz
Maximum Amplitude of Jitter Induced Sidebands (10
kHz 0 dBFS test tone, 12.75 UI sinusoidal jitter at 1
kHz)
< -144 dB
Maximum Amplitude of Spurious Tones with 0 dBFS test
signal
< -138 dB
Maximum Amplitude of Idle Tones
< -147 dB
Maximum Amplitude of AC line related Hum & Noise
< -140 dB
Inter-channel Differential Phase (Stereo Pair – any
sample rate)
+/- 0.25 degrees at 20 kHz
Inter-channel Differential Phase (Between DAC2 HGC
Units Fs<110 kHz) Any sample rate.
+/- 0.25 degrees at 20 kHz
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 69
Page 70
Audio Performance (continued)
Maximum Lock Time after Fs change
400 ms
Soft Mute Ramp Up/Down Time
50 ms
Mute on Receive Error
Yes
Mute on Lock Error
Yes
Mute on Idle Channel
No
50/15 us De-Emphasis Enable
Automatic in Consumer Mode
De-Emphasis Method
Digital IIR
De-Emphasis Supported at
Fs = 32, 44.1, 48 kHz
Group Delay (Latency)
Delay – Digital Input to Analog Output (function of
sample rate)
1.36 ms at 44.1 kHz
1.27 ms at 48 kHz
0.90 ms at 88.2 kHz
0.82 ms at 96 kHz
0.51 ms at 176.4 kHz
0.47 ms at 192 kHz
Digital Audio Inputs
Number of Digital Inputs (switch selected)
6 (1 USB, 2 Optical, 1 AES, 2 Coaxial)
Number of Channels
2
Input Sample Frequency Range
28 to 210 kHz (Coaxial and XLR)
28 to 96 kHz (Optical)
44.1, 48, 88.2, 96, 176.4, 192 kHz
(USB)
Maximum Input Word Length
24 bits
Digital Input Impedance
75 Ohms Coaxial, 110 Ohms XLR
DC Blocking Capacitors on Digital Inputs
Yes (Coaxial and XLR Inputs)
Transient and Over-Voltage Protection on Digital Inputs
Yes (Coaxial and XLR Inputs)
Transformer Coupling on Digital Inputs
Yes (XLR Input)
Minimum Digital Input Level
250 mVpp (Coaxial and XLR Inputs)
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 70
Page 71
Jitter Tolerance
(With no Measurable Change in Performance)
>12.75 UI sine, 100 Hz to 3 kHz
>1.5 UI sine at 20 kHz
>1.5 UI sine at 40 kHz
>1.5 UI sine at 80 kHz
>1.5 UI sine at 90 kHz
>0.25 UI sine above 160 kHz
Jitter Attenuation Method
Benchmark UltraLock2™ - all inputs
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 71
Page 72
Balanced Analog Outputs
Number of Balanced Analog Outputs
2
Output Connector
Gold-Pin Neutrik™ male XLR
Output Impedance
60 Ohms (Attenuator off)
425 Ohms (Attenuator = 10 dB)
135 Ohms (Attenuator = 20 dB)
Analog Output Clip Point
+30 dBu
Factory Set Bypass Level (at 0 dBFS)
+24 dBu (Attenuator = 0 dB)
Output Level Range (at 0 dBFS) In ‘Variable’ Mode
Off to +24 dBu (Attenuator off)
Off to +14 dBu (Attenuator = 10 dB)
Off to +4 dBu (Attenuator = 20 dB)
Output Level Variation with Sample Rate (44.1 kHz vs.
96 kHz)
< +/- 0.006 dB
Unbalanced Analog Outputs
Number of Unbalanced Analog Outputs
4
Output Connector
RCA
Output Impedance
30 Ohms
Analog Output Clip Point
+13.5 dBu
Factory Set Home Theater Bypass Output Level (at 0
dBFS)
+8.2 dBu (2 Vrms)
Output Level Range (at 0 dBFS)
Off to +8.2 dBu
Output Level Variation with Sample Rate (44.1 kHz vs.
96 kHz)
< +/- 0.006 dB
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 72
Page 73
HPA2TM Headphone Outputs
Number of Headphone Outputs
2
Output Connectors
¼” TRS with switch on left-hand jack
Output Impedance
< 0.11 Ohms
Output Level Control
Stereo Control on Front Panel
Output Level Range (at 0 dBFS) into 60-Ohm Load
Off to +17 dBu
Maximum Output Current
250 mA
Overload Protection (independent per channel)
Current limited at 300 mA, Thermal
Bandwidth
> 500 kHz
THD+N
-106 dB, 0.0005% into 30 Ohms at
+18 dBu (1.26W)
Status Display
Indicators - Type and Location
16 LED’s on Front Panel
Selection/Status Indication
2 – Dim/Mute
6 – Input
2 – Bypass/Calibrated Output
2 – Word length
4 – Sample Rate
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 73
Page 74
AC Power Requirements
Nominal Input Operating Voltage Range (VAC RMS)
100 – 240V
Frequency
50-60 Hz
Power
< 0.5 Watts Idle
12 Watts Typical Program
15 Watts Maximum
Fuses
5 x 20 mm (2 required)
0.5 A 250 V Slo-Blo® Type
Min/Max Operating range (VAC RMS)
90 – 260
47 – 63Hz
Dimensions
Form Factor
½ Rack Wide, 1 RU High
Depth behind front panel
8.5” (216 mm)
Overall depth including connectors but without power
cord
9.33” (237 mm)
Width
9.5” (249 mm)
Height
1.725” (44.5 mm)
Weight
DAC2 only
3 lb.
DAC2 with remote control, power cord, extra fuses, and
manual
4 lb.
Shipping weight
7 lb.
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 74
Page 75
Regulatory Compliance
RoHS Compliance Information
This statement clarifies Benchmark Media Systems, Inc. product compliance with the EU’s
(European Union) directive 2002/95/EC, or, RoHS (Restrictions of Hazardous Substances).
As of July 01, 2006, All Benchmark Media Systems, Inc. products placed on the European Union
market are compliant (containing quantity limit weight less than or equal to 0.1% (1000 ppm)
of any homogeneous Lead (Pb), Mercury (Hg), Hexavalent Chromium (Cr VI), and flame
retardant Polybrominated Biphenyls (PBB) or Polybrominated Diphenyl Ethers (PBDE)).
FCC Notice (U.S. Only)
NOTICE: This equipment has been tested and found to comply with the limits for a Class B
digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide
reasonable protection against harmful interference in a residential installation. This equipment
generates, uses, and can radiate radio frequency energy and, if not installed and used in
accordance with the instructions, may cause harmful interference to radio communications.
However, there is no guarantee that interference will not occur in a particular installation. If
this equipment does cause harmful interference to radio or television reception, which can be
determined by turning the equipment off and on, the user is encouraged to try to correct the
interference by one or more of the following measures:
Reorient or relocate receiving antenna.
Increase the separation between the equipment and receiver.
Connect the equipment into an outlet on a circuit different from that to which the receiver is
connected.
Consult the dealer or an experienced radio/TV technician for help.
This device complies with Part 15 of the FCC rules. Operation is subject to the following two
conditions:
1. This device may not cause harmful interference.
2. This device must accept any interference received including interference that may cause
undesired operation.
Instructions to Users: This equipment complies with the requirements of FCC (Federal
Communication Commission) equipment provided that following conditions are met:
RCA Digital Connections: Shielded 75-Ohm coaxial cable must be used.
NOTICE: Changes or modifications not expressly approved by the party responsible for
compliance could void the user's authority to operate the equipment.
FCC and RoHS Compliance Statements
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 75
Page 76
CE Certificate of Conformity
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 76
Page 77
Warranty Information
The Benchmark 1-Year Warranty
Benchmark Media Systems, Inc. warrants its products to be free from defects in material and
workmanship under normal use and service for a period of one year from the date of
delivery.
This warranty extends only to the original purchaser. This warranty does not apply to fuses,
lamps, batteries, or any products or parts that have been subjected to misuse, neglect,
accident, modification, or abnormal operating conditions.
In the event of failure of a product under this warranty, Benchmark Media Systems, Inc. will
repair, at no charge, the product returned to its factory. Benchmark Media Systems, Inc. may,
at its option, replace the product in lieu of repair. If the failure has been caused by misuse,
neglect, accident, or, abnormal operating conditions, repairs will be billed at the normal shop
rate. In such cases, an estimate will be submitted before work is started, if requested by the
customer.
Attempts to deliberately deface, mutilate, or remove the product's label will render this
warranty void. Benchmark will not honor warranties for any products disingenuously purchased
on the US or Canadian markets for export.
The foregoing warranty is in lieu of all other warranties, expressed or implied, including but not
limited to any implied warranty of merchantability, fitness or adequacy for any particular
purpose or use. Benchmark Media Systems, Inc. shall not be liable for any special, incidental,
or consequential damages, and reserves the right to change this information without notice.
This limited warranty gives the consumer-owner specific legal rights, and there may also be
other rights that vary from state to state.
Benchmark 1-Year Warranty
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 77
Page 78
The Benchmark Extended 5-Year Warranty *
Benchmark Media Systems, Inc. optionally extends the standard 1-year warranty to a period of
five years from the date of delivery.
*For the extended warranty to become effective, the original purchaser must register the
product at the time of purchase either by way of the enclosed registration card or through the
product registration section of the Benchmark Media Systems, Inc. website. This optional
warranty applies only to products purchased within the US and Canada and is extended only to
the original purchaser.
Attempts to deliberately deface, mutilate, or remove the product's label will render this
warranty void. Benchmark will not honor warranties for any products disingenuously purchased
on the US or Canadian markets for export. The terms of the extended warranty are subject to
change without notice. For products purchased outside the US and Canada, please refer to the
Extended Two 2-Year International Warranty.
The Benchmark Extended 2-Year International Warranty **
Benchmark Media Systems, Inc. optionally extends the standard 1-year warranty to a period of
two years from the date of delivery.
**For the extended warranty to become effective, the original purchaser must register the
product at the time of purchase either by way of the enclosed registration card or through the
product registration section of the Benchmark Media Systems, Inc. website. This optional
warranty applies only to products purchased outside the US and Canada and is extended only
to the original purchaser.
Attempts to deliberately deface, mutilate, or remove the product's label will render this
warranty void. Benchmark will not honor warranties for any products disingenuously purchased
on the US or Canadian markets for export. The terms of the extended warranty are subject to
change without notice. For products purchased in within the US and Canada, please refer to the
Extended Five 5-Year Warranty.
Notes on Warranty Repairs
An RMA (return merchandise authorization) number, issued by our Customer Service
Department, is required when sending products for repair.
They must be shipped to Benchmark Media Systems prepaid and preferably in their original
shipping carton with the RMA number clearly visible on the exterior of the packaging. A letter
should be included giving full details of the difficulty.
Benchmark Extended Warranty Options
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 78
Page 79
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Benchmark Media Systems, Inc.
All rights reserved.
Benchmark Media Systems, Inc.
203 East Hampton Place, STE 2
Syracuse, NY 13206-1633
USA
PHONE: +1-315-437-6300
FAX: +1-315-437-8119
www.benchmarkmedia.com
Instruction Manual for DAC2 DX with 2.X Firmware - Rev. B Page 79
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