http://code.google.com/p/android/issues/de...Summary%20Stars
Star: Vote by clicking on the star
According to Android specifications, Android 4.X devices could support the USB audio feature, i.e. Android 4.X devices and USB_CLASS_AUDIO compliant devices like standard USB DAC could interoperate:
http://developer.android.com/guide/topics/usb/index.html
http://developer.android.com/reference/and...bConstants.html
USB_CLASS_AUDIO compliant devices like standard USB DAC don’t need a special USB device driver. Instead, they use an operating system standard driver.
The Android standard USB audio driver is the generic USB Audio Driver for ALSA (Advanced Linux Sound Architecture).
And the latest Android 4.X includes “card.c“, the USB Audio Driver for ALSA which should be compliant with USB audio class 2 devices allowing for 24 bits / 192 kHz.
https://bitbucket.org/paulobrien/android_ke...ound/usb/card.c

Android relies on Linux version 2.6 for core system services such as security, memory management, process management, network stack, and driver model. The Linux kernel also acts as an abstraction layer between the hardware and the rest of the software stack.
Thus Android handles all the things that Linux is really good at such as a vast array of device drivers, which take the pain out of interfacing to peripheral hardware.
Most USB DAC work without special USB device driver on PC, Mac and hopefully Android 4.X devices with USB audio enabled.
Some USB DAC:
. Portable FiiO USB DAC/amp:
http://www.fiio.com.cn/product/
. Portable iBasso USB DAC/amp:
http://www.ibasso.com/en/products/
. Portable RSA USB DAC/amp:
http://www.raysamuelsaudio.com/products/predator
. Portable HeadAmp USB DAC/amp:
http://www.headamp.com/pico/pico_dac_amp/index.htm
. Portable GoVibe USB DAC/amp:
http://jaben.net/shopping2/Porta-Tube_Plus.html
. Desktop CEntrance USB DAC/amp:
http://centrance.com/products/
. Desktop USB DAC MSB DAC IV:
http://www.msbtech.com/products/platinumHome.php
....
About external USB DAC/Amp
A digital audio system is composed of:

. A storage module: Music is stored in file as a series of bits 0 & 1 with different encoding formats (MP3, WAV, FLAC…).
. A player: The player decodes the bits 0 & 1 to PCM digital audio signals.
. A DAC (Digital to Analog Converter): The DAC converts the PCM digital audio signals to the original analog audio signals.
. An amplifier: The amplifier amplifies the analog audio signals.
. A speaker: The speaker restitutes the music.
Like a PC or a Mac, an Android phone is a digital audio system.

Hopefully, the Android phone, running on a kernel with a USB audio driver, can output the PCM digital audio stream to an external standard USB DAC & amplifier & headphone, much more efficient than the internal DAC & amplifier & speakerphone.

A list of stock Android-powered devices reportedly interworking with standard USB DAC:
stock Android device > digital USB audio out >> standard USB DAC >> amp >> headphones
. Acer Iconia Tab A200 using USB Audio Recorder PRO (tablet):
http://www.engadget.com/2012/03/15/acer-ic...ab-a200-review/
http://www.extreamsd.com/USBAudioRecorderPRO/
. Acer Iconia Tab A500 using USB Audio Recorder PRO (tablet):
http://www.engadget.com/2011/04/26/acer-ic...ab-a500-review/
http://www.extreamsd.com/USBAudioRecorderPRO/
. Archos G9 (tablet):
http://www.anandtech.com/show/5802/the-arc...ews-fast-enough
http://forum.xda-developers.com/showthread.php?t=1539576
. Asus TF101 using USB Audio Recorder PRO (tablet):
http://www.engadget.com/2011/04/18/asus-ee...edition-review/
http://www.extreamsd.com/USBAudioRecorderPRO/
. Asus TF201 using USB Audio Recorder PRO (tablet):
http://www.tomshardware.com/reviews/transf...eview,3175.html
http://www.extreamsd.com/USBAudioRecorderPRO/
. Asus TF300 using USB Audio Recorder PRO (tablet):
http://www.engadget.com/2012/04/22/asus-tr...d-tf300-review/
http://www.extreamsd.com/USBAudioRecorderPRO/
. Asus TF700 using USB Audio Recorder PRO (tablet):
http://www.engadget.com/2012/06/25/asus-tr...y-tf700-review/
http://www.extreamsd.com/USBAudioRecorderPRO/
. Asus Transformer Prime using USB Audio Recorder PRO (tablet):
http://www.engadget.com/2011/12/01/asus-ee...r-prime-review/
http://www.extreamsd.com/USBAudioRecorderPRO/
. Google Galaxy Nexus using USB Audio Recorder PRO (smartphone):
http://www.theverge.com/products/galaxy-nexus-gsm/2946
http://forum.xda-developers.com/showpost.p...69&postcount=52
. Google Nexus 7 using USB Audio Recorder PRO (tablet):
http://www.engadget.com/2012/06/28/nexus-7-review/
http://www.extreamsd.com/USBAudioRecorderPRO/
. Google Nexus 10 using USB Audio Recorder PRO (tablet):
http://www.engadget.com/2012/11/02/nexus-10-review/
http://www.head-fi.org/t/595071/android-ph...10#post_8973836
. HTC Butterfly / HTC Droid DNA / HTC J Butterfly (smartphone):
http://www.htc.com/www/smartphones/htc-butterfly/
http://www.head-fi.org/t/595071/android-ph...25#post_9082851
. HTC One X (smartphone):
http://www.engadget.com/2012/04/02/htc-one-x-review/
http://forum.lowyat.net/index.php?showtopi...entry57944246
. Huawei Ascend D1 Quad XL using USB Audio Recorder PRO (smartphone):
http://www.engadget.com/2012/10/20/huawei-...quad-xl-review/
http://www.head-fi.org/t/628254/fiio-e18/15#post_8988466
. Huawei MediaPad using USB Audio Recorder PRO (tablet):
http://www.androidnz.net/2012/09/rapid-rev...adt-mobile.html
http://www.extreamsd.com/USBAudioRecorderPRO/
. iMito MX1 (mini PC):
http://www.squidoo.com/imito-mx1-android-mini-pc-bluetooth
http://www.armtvtech.com/armtvtechforum/vi...&t=669&start=10
. MK808 / MK808B (mini PC):
http://www.squidoo.com/mk808-dual-core-and...-mini-pc-review
http://tabletrepublic.com/forum/android-mi...ongle-3092.html
. Meizu MX Quad-Core using USB Audio Recorder PRO (smartphone):
http://www.xda-developers.com/android/meiz...ad-core-review/
http://www.extreamsd.com/USBAudioRecorderPRO/
. Minix Neo G4 (mini PC):
http://www.squidoo.com/minix-neo-g4-review
http://www.facebook.com/minixtech/posts/466648763397297
. Minix Neo X5 (mini PC):
http://tabletrepublic.com/forum/android-mi...eview-3241.html
http://forum.audiogon.com/cgi-bin/fr.pl?dd...20&openflup&5&4
. Motorola Razr Maxx HD using USB Audio Recorder PRO (smartphone):
http://www.engadget.com/2012/10/19/droid-r...maxx-hd-review/
http://www.extreamsd.com/USBAudioRecorderPRO/
. Motorola Xoom using USB Audio Recorder PRO (tablet):
http://www.engadget.com/2011/02/23/motorola-xoom-review/
http://www.extreamsd.com/USBAudioRecorderPRO/
. Samsung Galaxy Camera (camera):
http://www.digitaltrends.com/digital-camer...k-gc100-review/
http://www.sogi.com.tw/android/article_lis...opic_ID=6205384
. Samsung Galaxy Note II (smartphone):
http://www.engadget.com/2012/10/08/samsung...note-ii-review/
http://www.head-fi.org/t/595071/android-phones-and-usb-dacs
. Samsung Galaxy Note 10.1 (tablet):
http://phandroid.com/samsung-galaxy-note-10-1/
http://www.head-fi.org/t/595071/android-ph...45#post_8814831
. Samsung Galaxy R using USB Audio Recorder PRO (smartphone):
http://www.engadget.com/2011/08/10/samsung...and-asia-nobod/
http://www.extreamsd.com/USBAudioRecorderPRO/
. Samsung Galaxy S III (smartphone):
http://www.theverge.com/2012/5/25/3042640/...xy-s-iii-review
http://www.head-fi.org/t/595071/android-phones-and-usb-dacs
. Samsung Galaxy Tab 2 7.0 using USB Audio Recorder PRO (tablet):
http://www.engadget.com/2012/04/11/samsung...b-2-7-0-review/
http://www.extreamsd.com/USBAudioRecorderPRO/
. Samsung Galaxy Tab 7.7 using USB Audio Recorder PRO (tablet):
http://www.engadget.com/2012/02/07/samsung...tional-edition/
http://www.extreamsd.com/USBAudioRecorderPRO/
. Samsung Galaxy Tab 10.1 using USB Audio Recorder PRO (tablet):
http://www.engadget.com/2012/05/15/samsung...-2-10-1-review/
http://www.extreamsd.com/USBAudioRecorderPRO/
. Sony Tablet S / S1 using USB Audio Recorder PRO (tablet):
http://en.wikipedia.org/wiki/Sony_Tablet_S1
http://www.head-fi.org/t/595071/android-ph...25#post_9176002
. Sony Xperia P using USB Audio Recorder PRO (smartphone):
http://www.engadget.com/2012/06/03/sony-xperia-p-review/
http://www.head-fi.org/t/595071/android-ph...35#post_9131701
. Sony Xperia S using USB Audio Recorder PRO (smartphone):
http://www.engadget.com/2012/03/08/sony-xperia-s-review/
http://www.extreamsd.com/USBAudioRecorderPRO/
. Sony Xperia Sola using USB Audio Recorder PRO (smartphone):
http://www.androidcentral.com/device/sony-xperia-sola
http://www.extreamsd.com/USBAudioRecorderPRO/
. Sony Xperia Z (smartphone):
http://www.engadget.com/2013/02/20/sony-xperia-z-review/
http://www.youtube.com/watch?v=kgNkOs9o1dU
. Toshiba Thrive using USB Audio Recorder PRO (tablet):
http://www.engadget.com/2011/07/22/toshiba-thrive-review/
http://www.extreamsd.com/USBAudioRecorderPRO/
. Wiko Cink King using USB Audio Recorder PRO (smartphone):
http://www.wikomobile.com/telephone-portable-Cink-king.php
http://www.extreamsd.com/USBAudioRecorderPRO/

The compatibility list of Android devices / USB DAC is regularly updated at the following topic:
Android phones and USB DACs
We should put pressure on Google, and therefore on the Android device manufacturers.
USB audio is included in Android 3.1 or newer platforms.
http://developer.android.com/guide/topics/usb/index.html
It is up to Google for its reference Nexus and the other Android device manufacturers to support or enable the USB audio feature on their devices.
An example:
Interworking between Archos G9 tablet and USB DAC FiiO E17:
http://www.jbmm.fr/2012/01/utiliser-le-dac...vec-son-archos/

The Archos G9 tablet is powered by Android 3.2 Honeycomb.
http://www.archos.com/products/gen9/archos...ntry=us&lang=en
http://update.archos.com/9/gen9/changes_fi...ndroid_gen9.htm
Version 3.2.22 - September 2nd, 2011: USB audio not supported
Initial Honeycomb 3.2 firmware release
Version 3.2.77 - December 6th, 2011
Accessories: external USB audio cards (DAC) support has been added
Version 3.2.78 - December 19th, 2011
Audio accessory: fix USB DAC not supporting 44.1kHz
Added on February 11, 2012, 11:01 pmThe official Android with USB audio enabled should be used by most people, who don’t want to mod their devices.
A die-hard audiophile minority should likely use audio-optimized Android kernels modded by some kernel modders.
"An interesting example is the HRT music streamer II, it IS asynchronous USB, but it is still very sensitive to what happens in the computer. On the SAME COMPUTER I can make simple changes to OS scheduling parameters and get a huge difference in the sound. At one end of the scale it’s dull, lifeless, no depth at all, at the other end of the scale it is wonderfully alive, dynamic, huge depth etc. And all this by just changing a few numbers, NO change in hardware at all."
http://www.audioasylum.com/cgi/m.pl?forum=pcaudio&n=101397
For example, an underclocked kernel should be better than a normal kernel to provide a lesser jittered digital audio stream to a USB DAC, because the USB transmission clock is less polluted by electric and electromagnetic interferences generated by different processors.
Anyway, Android kernel modders have already enabled the USB audio feature on Nook Color tablets which are powered by Android 2.3 Gingerbread.
http://forum.xda-developers.com/showpost.p...3&postcount=587
Added on February 13, 2012, 11:25 pmThank you for your votes!
The USB audio request is currently ranked 50, and there are 17550 requests.
http://code.google.com/p/android/issues/de...Summary%20Stars
In fact, it is ranked in top 10 of less than one year old requests.
An Android kernel developer is trying to enable the USB audio feature (i.e. to allow interoperability between Samsung Galaxy S2 and USB DAC).
He is looking for testers.
"Anyone have a dmesg log when connecting a DAC device? I don't use one so I can't test and get logs. If you need DAC support you'll need to help out here. If not, I can simply remove support for it in 1.4 since it doesn't work right and I can't test it."
http://forum.xda-developers.com/showpost.p...postcount=10082
Red Pill Kernel
RedPill_Rev1.3
Experimental: USB Audio support for DAC devices
http://forum.xda-developers.com/showthread.php?t=1288850
The official USB audio request is currently ranked 33 of 17817.
http://code.google.com/p/android/issues/de...Summary%20Stars
In fact, it is ranked in top 4 of less than one year old requests.
Vote: Click on the star
Thank you for your votes!
Why not a battery-powered USB hub?
This post has been edited by DanBa: Mar 2 2013, 06:58 PM
Feb 11 2012, 08:50 PM, updated 12y ago
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