April Music Stello DA100 Signature User Manual

Thank you for buying the Stello DA100 Signature. Unpretentious in appearance, the
DA100 Signature digital-to-analog converter packs stunning performance in a
compact form.

Like its sibling DA100, the Signature version is a high-end audiophile DAC, featuring
high-resolution 24 Bit / 192 kHz upsampling. Many of the features of our legendary
DA220 DAC have been incorporated in the smaller platform of the DA100 Signature.

In addition to coaxial, Toslink and AES / EBU inputs, the DA100 Signature has a USB
(Universal Serial Bus) standard port for wide PC applications. You'll experience
computer audio like never before.

Unlike the DA100, the Signature features support for
mini-DIN connector.
clock, word clock, bit clock, and audio data.

The DA100 Signature's fully-balanced analog outputs are on Neutrik connectors.

Try the DA100 Signature with any of your digital sources – computer, CD, DVD, cable
or satellite TV receiver. You'll be amazed how digital sound can be transformed into
something musically seductive and emotionally satisfying.

The DA100 Signature is made especially for those who understand the importance of
music in our daily lives!

Sit back, relax and enjoy the music!

I²S sends separate signals on individual conductors for master

I²S digital transmission via a

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DA100 Signature Overview

An Elegant High-End D/A Converter

Simple to use and elegant in appearance, April Music's DA100 Signature is a
reference-quality high-end digital-to-analog converter incorporating state-of-the-art
technology. Tuned for pure reproduction of music, it's not merely a DAC but a true
high-end solution for serious audiophiles.
The DA100 Signature is equipped with high-performance circuitry usually found in
much more expensive equipment, including its special digital input receiver, true 24
Bit / 192 kHz upsampling circuit, jitter-free timing circuit, and 6th-order digital filter. Its
DAC chipset and fully discrete class A analog output stage are features found in DACs
priced four or five times higher than the DA100. Premium features include 1%
tolerance metal film resistors, WIMA polypropylene capacitors, Cardas RCA connectors,
and Neutrik balanced connectors.
Promising long-term, problem-free performance that will prove musically satisfying to
even the most demanding listeners, the DA100 Signature is ruggedly but beautifully
built, like all April Music products.

Five Digital Inputs, including USB and I²S

The DA100 Signature has five digital inputs: one coaxial, one AES / EBU, one optical
(Toslink), for use with disc players, cable TV receivers, gaming consoles and the like;
one USB connector for use with personal computers, and one I
similarly-equipped disc transports.
For a startling upgrade to typical computer sound, simply connect your desktop or
notebook computer to the DA100 Signature using the supplied USB cable. You will be
amazed by the dramatic improvement. Even highly compressed 128k MP3 files are
raised to a level approximating original WAV files, thanks to special circuitry designed
only for the DA100 Signature.
The DA100 Signature is useful for more than music, upgrading the sound of DVDs,
television programs, and movie files in your computer. All digital sources are tremen
dously improved with the April Music DA100 Signature.
Sound effects in video games take on a new realism, too, with wide soundstage,
detailed micro-dynamics, and huge impact. Such effects were previously possible only
with the most costly DACs on the market.
The Signature also supports I²S, widely believed to be the most accurate and most
revealing interface for digital audio. With separate conductors carrying signals for
master clock, word clock, bit clock, and audio data, I
many recordings. High-quality CD transport with I

²S will truly "lift the veil" from

²S output (such as the Stello

CDT100) and the DA100 Signature DAC make an unbeatable source combination.
A versatile reference-quality DAC for a wide variety of applications, the DA100
Signature is the most cost-effective upgrade you can make to your audio system.

²S for use with

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Premium Quality Components

The components used in the DA100 Signature are true high-end audiophile grade.
Premium chipsets include the digital receiver, 24 bit / 192 kHz upsampling chip and
the digital-to-analog converter, with 120 dB dynamic range.
Superior quality audio playback is further guaranteed by the use of premium quality
passive components throughout, including WIMA polypropylene capacitors and 1%
tolerance resistors. Enhanced longevity is made possible by specially-selected
gold-plated RCA connectors and low-noise switches.
All internal parts exceed industrial standards. Look carefully inside the DA100
Signature and you will easily discover why this unit sounds so amazing.

Oversized Power Supply

A generous power supply is the heart of every great-sounding audio component. The
DA100 Signature's power supply is specially designed, with a 25 VA custom-made
Toroidal power transformer providing an ample supply of energy for digital and
analog circuitry in the DA100 Signature. The voltage regulation circuit has very low
output impedance (20 m

Ω@10 Khz). Extremely stable voltages combined with

instantaneous current delivery mean ultra-low residual noise in the Signature's output.
This translates to silent sonic backgrounds and lifelike musical details.

You can easily change supply voltage by selecting the proper one with
the slide switch, located on upper left-hand corner on the main pcb. From 100~120 V
to 220~240 V / 50~60 Hz, you can use DA100 Signature anywhere in the world.

Analog Output Stage

Fully Class A push-pull throughout, the analog output stage of the DA100 Signature is
a current-based amplifier design, for virtual immunity to electrical noise induced by
adjacent circuitry. This results in extremely high signal-to-noise and dynamic range
specifications, among the best in the world. Voltage conversion takes place in the
final stages of the circuit for maximum sonic transparency.

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Front Panel

STANDBY : A push-button front panel standby switch is used for normal and standby

operation. An illuminated red LED above it indicates the DA100 Signature is operating.
The actual power switch is on the rear panel and should remain on continuously.

UPSAMPLE : AES / EBU, S/PDIF (Coax), Optical (Toslink) and USB Input modes:

You can select either 24 Bit /192kHz upsampling (green LED), 24 Bit / 96 kHz upsam
pling (red LED) or Bypass (no LED). ‘BYPASS’ means the digital output is exactly same
as the digital input (up to 24 Bit / 96 kHz). Which mode is better? You be the judge.
Musicality and nuance vary depending on the recording status of the sources.
Generally, we recommend 192 kHz upsampling for most playback.

LOCK : Green color LED indicates that an input digital signal has been detected by

DA100 Signature.

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INPUT : Select any input you want to hear from any of the five digital inputs :

1 AES / EBU, 1 S/PDIF Coaxial, 1 Optical, 1 USB (Universal Serial Bus), and I

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²S.