XMOS DSD 192kHz USB DAC with Bit-perfect volume control CS4398

CS4398 is the flagship model of Cirrus Logic who acquire Wolfson Microelectronics. It features DSD playback, low clock jitter sensitivity and advanced non-decimating software volume control.

This USB DSD DAC combo includes XMOS USB to I2S with three ultra low phase noise NDK2520SD oscillator PCB, CS4398 DSD DAC PCB and an optional LED sampling rate indicator PCB.

Apart from the DSD playback functionality, it uses low noise thin film resistor, C0G capactor in the LPF, WIMA decouple cap, panasonic low ESR aluminum electrolytic capacitor and optimized layout 2mm distance for all decouple capacitor, etc.

The most distinctive features of this USB DSD DAC is our customize firmware for bit-perfect volume control. Most people may not notice many so called "bit-perfect" device on the market is bit-perfect ONLY When You Play At FULL Volume. If the volume is not set to maximum in the computer, the audio data is scaled/altered before sending to the DAC chip and the result is signal to noise ratio seriously affected.
Related paper on this important feature:
http://www.esstech.com/PDF/digital-vs-analog-volume-control.pdf

Compare on the audio data flow path:
General device on the market: "Partial" Bit-perfect only at full volume
Computer -> USB -> XMOS/CMxxxx/AMxxxxx -> I2S(audio data scaled/altered if not at full volume) -> DAC Chip (es9018/cs4398/pcm1794 etc.)

This USB DSD DAC: Complete Bit-perfect at any volume
Computer -> USB -> XMOS -> I2S(audio data bit perfect at any volume)+IIC volume control -> DAC Chip (es9018/cs4398/pcm1794 etc.)

After many hours of work on customize the xmos firmware on this USB DSD DAC, audiophiles can move the volume control bar up and down freely in the computer volume mixer panel and still enjoy bit perfect audio. DSD audio as well as PCM audio can also be bit perfect volume control easily from the computer. Please notes there are many so called bit-perfect device can play DSD but you must set the computer master volume control to full volume.

 FAQ:

1)Does the volume is controllable in WIN/MAC/LINUX when playing DSD using this combo? I find that I cannot control the DSD volume when using the other famous brand DSD USB output adapter
The DSD sound volume is controllable using our xmos DSD combo in all USB audio 2.0 compatible OS including WIN/MAC/LINUX system volume mixer.

2) Do I need to switch ASIO driver everytime when playing between PCM and DSD music file? I find it's annoying to do it when using the other famous brand DSD USB output adapter.
Our xmos combo can use the same output ASIO: foo_dsd_asio in foorbar2000 to play PCM and DSD music file. No need to switch output everytime to play.

3)Is the xmos i2s Bit-perfect volume control PCB in the combo can be used connect to other DAC chip?
Different DAC chip require different IIC volume control command and different DSD PCM switch command. The XMOS PCB in this combo is designed only for use in this combo.

4)Is circuit schemetic available?
The circuit mostly follows the official datasheet, it can be download from the related official DAC website.
CS4398 : 120 dB, 24-Bit, 192 kHz Stereo D/A Converter with DSD Support

5)Some people told uses IIC software control can interference the DAC performance, is it true?
The IIC volume control is only active when you moving the volume bar to change the volume, it is totally stopped when not in use.

6)What sampling rate are supported?
44.1-192khz and DSD64

7)Any annoying pop sound when playing between PCM and DSD format?
No pop sound. The cs4398 has automute feature when switch between pcm and dsd.

8) I already have CS4398 DAC, why still buy this one?
This DAC includes DSD playback feature, bit perfect volume control, WIMA 3.3uF film capacitor on the Quiescent Voltage pin, high quality and selected components, optimized layout 2mm distance for all decouple capacitor. It takes the cirrus logic flagship dac CS4398 to it's level.

*The PCB required one 3.3V (>200mA), one 5V (>100mA) and one +-12V (>100mA) regulated power supply.

DSD playback steps using foobar2000 in Microsoft Windows and MAC:

1. Download the latest version of Foobar2000 from the official website -  http://www.foobar2000.org/download

2. Download the official ASIO output plug-in for Foobar2000 from http://www.foobar2000.org/components/view/foo_out_asio

3. Download the Super Audio CD Decoder plug-in for Foobar2000 from http://sourceforge.net/projects/sacddecoder/files/foo_input_sacd/

4: Install eveything and set the output to ASIO: foo_dsd_asio, config foo_dsd_asio output device to DXIO

http://www.google.com/search?q=foobar+dsd

*For bit perfect playback at any volume, please use the Windows/MAC OS default builtin system master volume mixer control. Don't use the foobar volume control, it scale/alter the audio data internally.