USB 2 D/A MKI - Digital to Analog Converter

 User's Manual
- 02/2006 - review (in german)
03/2006 Nr. 310 - pro-review (in german)
04/2006 #397- review (in greek)

The USB 2 D/A is an upsampling 24/192 DAC for use in high-end or pro audio environment. The high end hifi USB DAC USB 2 D/A supports 24bit/192kHz sampling frequency via S/PDIF COAX and AES/EBU, up to 24Bit/96kHz via TOSLink and 44.1kHz via USB. Furthermore it is designed to work as an external computer soundcard via USB 1.1 connection (no driver needed). To complete this feature the unit is equipped with a standard hifi-quality microphone amplifier, A/D-Converter and headphone amplifier. Improves the audio signal of any digital source: CD/DVD Player, PC, Notebook etc..

Interior view (Click on photo for magnified view.)    Rear view (Click on photo for magnified view.)   19" Rack Mounts                                                                   

No Op-Amps in signal path

The AQVOX USB 2 D/A was designed using innovative discrete technology. Only single transistors are used in the amplification stages. No integrated circuit amplifiers (OP-amps) and the latest state of the art components to sound most dynamic, highly detailed yet neutral and untiring. We believe the USB 2 D/A to be a unit with outstanding sound quality and an excellent value.

No overall feedback

Fully discrete (single transistors) Single Ended Class A amplification technology and the use of just one amplifier per balanced analog output stage provides you with today's best possible sound quality. The amplifier section runs without overall negative feedback. Thus the amplifier generates no dynamic distortions.

JitterEx precision-reclocking 192kHz/24Bit upsampling

Before digital to analog conversion all signals are upsampled and converted to 192kHz/24Bit (unless the bypass is activated). This procedure is advantageous because DACs can offer better performance at higher sampling rates. Upsampling enables filtering to take place far beyond the range of human hearing, as well as offering other, audible benefits, right across the audio band, including improved transient response and less ringing. This results in a more open, transparent sound, tighter bass and a generally more "musical" sound.

True balanced circuitry for entire analog signal path

Featured with an AES/EBU digital input and a balanced XLR analog output the USB 2 D/A is the best choice for professional users to monitor digital recordings. True balanced circuitry for entire analog signal path. The USB 2 D/A is also excellent for persons who strive for the highest level of sound quality from their home audio systems, as well as for computer users who like to get the best output quality from their Workstations or Notebooks. No need to use a low-fi inbuilt soundcard. Furthermore users can upgrade their micro hifi system (portable CD, MD... as far as they provide a digital output) to a real high-end solution.

To achieve best possible sound under windows, ASIO drivers are required.
Apple MAC and Linux do NOT need any ASIO drivers!


NEW - Installation instructions: ASIO driver for USB, WinAmp, Foobar2000, etc..

USB ASIO, DirectSound and kernel-streaming drivers
with these drivers you can go around the windows K-mixer.


The K-Mixer (kernel-mixer) is the mixing console inside windows, where all sound "channels" of a PC are routed trough.
Unfortuntely the K-mixer has an ( for audiophile and pro-users ) unwanted and audible habit, he resamples the audio signal.
Apple computers with USB connection do not have this k-mixer.

To avoid any alterations of the audio-stream we have collected some nice PC- software tools for you:

Audio-files playback software with flexible outputs and free driver support

Free music player software: WINAMP5 : http://www.winamp.com

Free music player software: Foobar :http://www.foobar2000.org
configuration information for Foobar2000 at WIKI from hydrogenaudio
http://wiki.hydrogenaudio.org/index.php?title=Foobar2000


Freeware ASIO driver:
http://www3.cypress.ne.jp/otachan/
(unpack files in .7z format with 7-ZIP)

Freeware ASIO driver:
http://www.asio4all.de

The most audiophile ASIO driver comes from AQVOX produces least jitter, is compatible with some other USB-DAC´s and plays with all Windows based mediaplayers/soundprograms. You can order this driver directly from us, just contact us here: contact form
The trialversion is free.

Computers, PC´s, Notebooks and other devices with an USB interface may be used as "audio-datasources ":
(the device must provide a so called"USB-Host" feature)

!!! Some devies need an firmware update to provide the required functionality, please check with the manufacturer or dealer:

About the matter: read out of Audio CD´s in highest quality and store or playback from a PC or MAC harddrive.

How and with what should be grabbed? ( Audio CD read out)
The (cleaned) Audio CD´s should be grabbed with slowest possible readout speed.
(for info: some CD/DVD devices in computers are not able to read out data with speeds under 4x)
Ideal for grabbing purposes is the freeware programm Exact Audio Copy (EAC) http://www.exactaudiocopy.de
Excellent error correction and bit-perfect: http://www.exactaudiocopy.org

EAC incorporates the most exact audiodata reading technology with the least jitter of all audiograbbing programms available now.

How and with what should be compressed?:( audio aata loss-less compression )
First choice is the normal WAV format, which produces the biggest files of all compression programms.
Here is nothing left out from the orioginal.
MP3 is NOT suitable for highest soundreproduction and highend applications. Even at lowest compression rates where just 10% of storing space (compared to the original WAV file) is saved, results in smaller sound stages with less depth. Here are room- and transientinformations left out during compression/reduction losses.

The compression programm FLAC ( http://flac.sourceforge.net ) and also Monkey belong to the group of Loss Less (only compression no reduction) compressors and saving ca. 50% storage space. This is far less as with a MP3 reduction can be saved, but without any losses, because a FLAC file can be restored to 100% of the original WAV file, and therefore FLAC has far better sound quality as MP3.

The ideal case looks like: CD is in the CD-drive, EAC finds the CD title in the CD database and writes all titles automatically and reads out the CD. FLAC is integrated in EAC and EAC writes the title-tags in the FLAC files. It can´t be much easyer and convinient!
The advantage of loss-less compression is, that the audiosignal is after the decompression 100% identical to the original music signal.

Fact list

1. No Op Amp in signal path

2. No Feedback-loop

3. Dual Mono DAC (2 x Burr Brown PCM1796)
    results in endless (optimal) channel-separation, more dynamic jet stability and less than neglible noise.

4. Current Amplification DAC to analog output-stage coupling.
    reduced amplification-stages, the totally absence of any feedback (no feedback) and driven in pure class-A operation.

5. Only passive elements are used in the filter-stages. Advantage: TOP-grade measurement-figures.
    This technic/design is unique.

6. Passive analog filters
    produces -because on principle- no dynamic distortions.

7. Single ended Class A amplifiers
    are known for musical and dynamic sound. But require Class A layout.

8. Sample rate converted to 195kHz independent of input sampling.
      independent of input frequency, ultra stable 195kHz clock produces extremely low jitter signal.

9. Precision internal clocks for jitter elimination.
      Temperature and ageing compensated oscillator-modules.

10. 4 digital inputs: AES/EBU, RCA (16bit/32kHz till 24bit/192kHz), Toslink (16bit/32kHz till 24bit/96kHz), USB 1.1 (6kHz till      16bit/48kHz) USB1.1 (USB2.0 compatible) Plug-n-Play no drivers needed (WINXP, WIN2000, WINSE, WIN98, and Mac OS X).

11. Independent integrated PC USB 1.1 sound system functionality.

12. Digital data transfer from any input to computer via USB.

13. A/D converter for USB with Microphone/Headset amplifier with 12-volt phantom power
      for microphones resulting in better sound.

14. Separate D/A converter for USB headphone amplifier.

15. XLR and RCA outputs.
     True balanced circuitry for entire analog signal path.

16. Sampling frequency indicator.

17. Digital de-emphasis.

18. Flat and dynamic roll off digital filter.

19. Selectable dither.

20. 3 selectable oversampling ratios.

21. 100V ...240V operating AC voltages.

22. Blue backlighted push-buttons.

23. Ultra clean switching power supply
      with special pre- and post filtering of AC power voltage.

24. Insensitive to AC voltage distortions, DC fragments, noise and voltage stability.

25. Full aluminium casted turning knobs with long-distance viewable pointers.

26. Full Aluminium extrusion casted and machined front panel and side profiles.

27. All capacitors in signal path are finest inductive free-type very low loss
      polypropylene capacitors.

28. Biological friendly lead-free CuAgSn silver solder.

29. PCB boards completely gold plated.

30. 1% metal-film resistors are used within the audio path.

31. 19" full-aluminium robust rack-mounts are available.

32. External dimensions (w / h / d): approx. 435 x 59 x 290 mm

33. Weight approx. 2.8 kg

*Product features, design, specifications, system requirements, and availability are subject to change without notice.

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