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 I²S digital transmission via a
mini-DIN connector. I²S sends separate signals on individual conductors for master
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!

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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 I²S for use with
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, I²S will truly "lift the veil" from
many recordings. High-quality CD transport with I²S 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.
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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 mΩ@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.
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 I²S.
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Rear Panel
DIGITAL INPUTS : 5 input ports are ready (AES / EBU, COAX, OPT, USB, I²S). Please
make sure that you have proper cables for each input.
COAX : Theoretically, all digital inputs have the same music quality.
But, we believe what we hear, and in the real world of hi-fidelity, COAX is typically
better than other connections. We recommend using a dedicated CD Transport to
enjoy super quality playback from your audio equipment.
AES / EBU : AES / EBU digital format interface is mainly used in high-end environ-
ments. It is the preferred balanced form of S/PDIF digital transmission.
I²S : This mini-DIN jack should connect to the I²S output on a similarly equipped CD
player or dedicated disc transport. I²S offers the advantage of separate conductors
and separate signals for bit clock, word clock, and audio data.
When I²S input is selected and DA100 Signature’s receiver receives I²S signal from the
digital source device (such as CDT100 CD transport’s transmitter), the signal is locked
and begins its operation.
Following is the pin assignment for DA100 Signature Mini DIN connector.
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Note:
I²S interface cable should be as short in length as possible with its master clock, word
clock, bit clock, and audio data in individually shielded cable for the best perfor-
mance. DA100 Signature takes the I²S signals in TTL level.
OPT :
Standard Optical input, known industrially as "Toslink" , from Toshiba. Most DVD
players, cable / HDTV receivers, game machines, and PC or notebook sound cards are
equipped with either COAX or Toslink outputs for connection to an external DAC.
With some devices, you'll need to use the “SETUP” menu to set the output mode of
the device to export digital signal through this port.
The DA100 Signature accepts PCM signals only.
Setting "Digital Out" mode as "PCM"
� From the DVD player's setup menu, go to Audio Setup → Digital Out → PCM.
� Many DVD or universal players today support digital output with ‘96kHz.’ If your
player has this option, set its output to ‘96 kHz.’ This ensures the highest resolution
from the source, because the DA100 Signature accepts up to 24 Bit / 96 kHz. You will
be stunned with the reproduced sound!
USB : Any USB (Universal Serial Bus) output can be connected to this
port.
� DA100 Signature does not support ASIO driver.
1
2
4
5
3
PIN 1 : word clock
PIN 2 : bit clock
PIN 3 : audio data
PIN 4 : master clock
PIN 5 : not connected
Shield : circuit ground

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DA100 Signature is designed for pure playback mode only.
ANALOG OUTPUTS :
There are left and right analog outputs on the back of the DA100 Signature. Connect
these outputs to your preamplifier or integrated amplifier, making sure the "left" and
"right" connections are correct. The DA100 Signature features unbalanced, single-
ended outputs on gold Cardas RCA connectors, and balanced outputs on Neutrik
connectors. Balanced operation is best for long cable runs, because it neutralizes
common-mode noise and noise from ground loops.

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Connection & Operation
How to connect
CD TRANSPORT
(AES/EBU OUTPUT) T100-CD TRANSPORT
(I2S OUTPUT)
DVD PLAYER
PC (USB OUTPUT) SET-TOP BOX

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How to operate
1) Make sure that the level of your preamplifier or integrated amplifier is set to a low
volume level.
2) Turn the ‘Power’ Switch up on the rear panel. Then push the ‘Standby’ button on
the front panel (Red LED will light).
3) Select your input by rotating the INPUT knob (AES / EBU, COAX, OPT, USB, I²S).
4) Check if the ‘LOCK’ signal is on. If the ‘LOCK’ LED is not on even though you set
the knob for your selection, please check the wiring again for proper connection.
5) Set the ‘UPSAMPLE’
Press UPSAMPLE push-button switch for 24 / 192 upsampling with green LED, or 24 /
96 upsampling with red LED or ‘BYPASS’ mode with LED off. You can change this
setting during playback without harming the DA100 Signature. The UPSAMPLE mode
will advance from BYPASS to 96, 192, and back to BYPASS whenever the UPSAMPLE
push-button is pushed momentarily. The default UPSAMPLE setting is 192.
USB output from your PC or Notebook
1) Connect your PC to the DA100 Signature with the bundled USB cable.
2) Your PC will automatically detect the DA100 Signature, flashing the notice ‘USB
DEVICE CONNECTED’ to indicate the connection.
3) Play audio or video files with your favorite player (Windows Media
Player, etc.)
4) If your PC or Notebook fails to detect USB as your main audio output, you should set
the default ‘Sound & Audio Device’ as ‘USB Audio’ in your PC's control panel. Select
‘Start’ → ‘Control Panel’ → ‘Sound & Audio Devices’ → ‘Audio’, then select ‘USB Audio
DAC.’
If you do not want to use DA100 Signature as your default output device, you may
change your setting again by selecting the supplied sound card output with the same
procedure.

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Features & Specifications
FEATURES
Digital input interface
- Strong protection against external interferences.
- Minimizes transmission errors.
- 200 mV sensitivity on all S/PDIF inputs.
Upsampling & D/A Converter
- Asynchronous Sampling Rate Conversion using a proprietary and specially designed
clock circuitry for extremely low jitter.
� ASRC characteristics
� Up sampling up to 192 kHz
- D/A converter upsampling characteristics
� D/A Converter characteristics
� Signal to Noise ratio : 120 db
� Dynamic range : 120 db
Preprocessing filter
-Custom designed sixth-order filter circuitry for minimal noise and isolation.
Analog output stage
- Class A Push-Pull output stage with fully discrete components.
- Balanced outputs on Neutrik connectors.
- Unbalanced outputs on Cardas gold RCA connectors.
Front display and control
- Standby power momentary push-button switch with LED indicator.
- Up-sampling and Bypass push-button switch with LED indicator.
- Digital input ‘LOCK’ LED indicator.
- 5-position digital input selection rotary switch.
Power supply
- Custom-made Toroidal transformer.

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SPECIFICATIONS
Digital inputs 1 AES / EBU, 1 COAXIAL, 1 TOSLINK, 1 USB, 1 I²S
Digital filter Proprietary 6th-order digital filter
Analog output 1 pair RCA unbalanced stereo,
Output voltage 2.4 Vrms@ 1 kHz
1 pair Neutrik balanced stereo
Polarity : (Pin2 : +, Pin3 : -, Pin1 : Ground),
Output voltage : 5.2 Vrms (2.6 Vrms@ each leg, 1 kHz)
Dynamic range 110 dB typical
Signal to Noise ratio 120 dB typical
Distortion 0.003 % 11 kHz
Frequency range 20 ~ 45 kHz
Sampling frequency ASRC : Bypass, 192 kHz
Digital input receiver : up to 96 kHz
Power consumption Standby : 18 Watts
Operating : 22 Watts
Power requirement 100~117 VAC / 220~240 VAC selectable
50 / 60 Hz
Dimension 212 mm (W) x 55 mm (H) x 290 mm (D)
Weight 3.5 kg (4.5 kg, 11 Lbs packaged)

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WARRANTY
April Music, Inc. supports 2 years of free warranty for the DA100 Signature under
normal use from the date of delivery.
This warranty extends only to the original purchaser and does not apply to parts that
have been subjected to misuse, or abnormal operations. DA100 Signature owners
who have purchased their units second hand can inherit the remaining waranty
period by contacting April Music, Inc. via e-mail or a letter to activate the remaining
warranty.
In the event of failure during the warranty period, April Music, Inc. will repair the
DA100 Signature at no charge as long as provided unit is in normal use.
If the unit is damaged by the abnormal use (incorrect voltage connection, spilling
coffee over the top etc.) and if you or your dealer cannot fix the problems, the unit
should be returned to the factory. In this case, the estimated repair fee (including
shipping & handling) will be submitted to you before shipping the unit for repair.
A return authorization is required when sending the units for repair. Returned units
must be shipped to April Music, Inc. prepaid and with original packaging (preferred).
There are no user serviceable parts inside except changing the line voltage. Beware
that the DA100 Signature runs very hot inside because the analog output stages are
class-A operated discrete circuits. Care should be taken.
If you or any unauthorized person have tried to change or modify the circuits without
any prior consent from April Music, Inc. all warranty will be voided even though the
units are still within the warranty period.
* Unauthorized person should not try to modify April Music products!

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Contact Information
April Music, Inc
Alpha Building, 894-18 Bangbae-Dong
Seocho-Gu, Seoul, Korea, 137-860
South Korea
Phone : [phone]
Fax : [phone]
Web : www.hifi500.com, www.aprilmusic.com
Purchasing inquiries : [email protected]om
Technical inquiries : [email protected]
April Music, USA
Sales Representatives
24521 SE Windsor Blvd.
Sammamish WA 98074, United States
Phone : [phone]
Fax : [phone]
Attn. Ki Choi
Mobile : [phone]
E-mail : k[email protected]
Attn. John Elison
Mobile : [phone]
E-mail : [email protected]

Manufactured by April Music, Inc.
contact [phone] (Seoul, Korea) [email protected]
www.hifi500.comwww.hifi500.com