[General Questions and Answers] chouck:
Here is a what I found on USB AUDIO output with Android (maybe it makes sense to put and update this table to the first topic)

NOTE: as of now SOME (not all!) USB AUDIO Android support implementations stream data through Android MUX that disturbs the original PCM stream for changing volume which means re-sampling original media, but also limited to 44.1kHz(some 48) 16 bit, so for SOME Android:

1) max all your volume controls while using external DAC

2) there is no reason to have / use DAC with higher rates then 44.1/16

3) there is no reason to have / use files of more then 44.1/16 quality. Trying to play 96kHz 24bit file will result in forcing Android to re-sample it on the fly with limited resources and not perfect algorithms leading to degrading output quality lower then proper done in studio or desktop 44.1/16!

There might be a way bypassing the Android layer and going right to ALSA you can do 24 bit.

If you specify a hardware device ("hw:0") in ALSA you can bypass any potential sample conversions.

*there is way around it in linux ALSA http://blog.agdunn.net/?p=434 but i have not seen such for Android

Supporting Devices

---------

Galaxy S III $700 Android phone

ARCHOS G9 $250+ Android tablet (looks like the key is OMAP chipset kernel drivers)

Squeezebox Touch $250 - propriatary logitech linux box

Ainol Novo 7/8 Advance 8gb 100$ Android tablet or Allwinner with a modded Android kernel

Nook Touch with custom rom

any A10 Android tablet http://www.slatedroid.com/topic/33373-rom-cm9-nightlies/

* Hyundai A7HD tablet with Cm9

* Mediacom 907c, Momo11 Bird, JXD S9000, Eken A90

* Visture V3

* Mediacom 910i, Teclast A10t

* ICOO D90W

* CEMA10N7 "unknown" device

* Bmorn V99

* Mediacom 711i, Momo9

* Protab2XXL

* Sanei N83

* Hyundai A7HD

* MOMO9 needs

http://xdaforums.com/showthread.php?p=22280857#post22280857

http://www.slatedroid.com/topic/29289-usb-audio-cards-support-drivers-and-libs/

. B&N Nook Colour with a modded Android kernel

http://xdaforums.com/showthread.php?t=1459892

. WitsTech A81G with a slightly modded Android kernel

http://android.modaco.com/topic/343858-external-usb-devices/page__st__20

Suported DACs:

for Galaxy S III

List of USB DACs with known USB controller that interwork with Samsung Galaxy S III for the time being:

+ AMB Labs Gamma2 with USB controller TI Burr-Brown PCM2707

+ FiiO E7 with USB controller TI Burr-Brown PCM2706

+ HifiMan Express with USB controller TI Burr-Brown PCM2702

+ Topping TP30 with USB controller TI Burr-Brown PCM2704

+ ODAC Tenor TE7022

List of USB DACs with known USB controller that don't interworking with Samsung Galaxy S III for the time being:

. FiiO E17 with USB controller Tenor TE7022

. iBasso D6 with USB controller TI TAS1020B

. Grant Fidelity TubeDAC-11 with USB controller Tenor TE7022

Hegel HD20 with USB controller Tenor TE7022 has also some issue

Audiotrak Prodigy Cube with USB controller Tenor TE7022

for Archos G9

+FiiO E17

+BEHRINGER UCA222

- E10 not supported

for Ainol Novo 7/8 Advance

+FiiO E7

+Burr-Brown PCM2704 USB DAC

+Creative

for Squeezebox Touch

+ Red Wine Audio Isabellina and an

+ HRT Music Streamer II+.

B&N Nook Colour

+Logitech DAC A-5572A |

+Beresford TC-7520SE Caiman |

+FiiO E7

B&N Nook Touch

+C-Media $5 USB adaptor

+Lexicon Alpha 24 bit adaptor

please reply here if you find more info on DAC/devices suppot so i'll keep this post up to date.