Edit: Android 5.0 Lollipop supports standard USB audio. Thank you!
http://www.avsforum.com/forum/173-2...id-4-0-smartphone-tablet-10.html#post28879001
If you want the USB audio enabled on any Android device via official firmware/kernel, please vote (aka star) here:
http://code.google.com/p/android/issues/detail?id=24614
Star: Vote by clicking on the star (it appears after signing in)
According to Android 3.1 specifications, Android devices could support the USB audio feature, i.e. Android devices and USB_CLASS_AUDIO compliant devices like standard USB DAC could interoperate:
http://developer.android.com/guide/t...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).
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 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/
. 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.
FAQ:
https://drive.google.com/file/d/0B3XYy1FuzDUea3U3aTJ1RkpQdW8/edit
A list of USB OTG cables / adapters:
https://drive.google.com/file/d/0B3XYy1FuzDUeUFBGX05GTjU2UWc/edit
A list of USB Type-C cables / adapters:
https://drive.google.com/file/d/0B3XYy1FuzDUeWnh1XzRtdHpoRGs/view?pli=1
A list of stock Android-powered devices reportedly interworking with compatible USB DAC:
stock Android device > digital USB audio out >> USB DAC >> amp >> headphones
https://drive.google.com/file/d/0B3XYy1FuzDUeX2t4TmJRbVZsaVE/edit
A list of USB Audio Player PRO resources (compatible USB DAC, compatible Android devices, ...):
http://www.extreamsd.com/USBAudioRecorderPRO/
A list of standard USB DAC reportedly interworking with the Android-powered smartphone Samsung Galaxy S3 having a microSD card slot:
stock Samsung Galaxy S3 > digital USB audio out >> USB OTG cable (ID pin grounded) >> USB DAC >> amp >>headphones
https://docs.google.com/file/d/0B3XYy1FuzDUeRFIxNWE2eDZ6aE0/edit?pli=1
A list of standard USB DAC reportedly interworking with the Android-powered smartphone Samsung Galaxy Note2 having a microSD card slot:
stock Galaxy Note2 > digital USB audio out >> USB OTG cable (ID pin grounded) >> USB DAC >> amp >>headphones
https://drive.google.com/file/d/0B3XYy1FuzDUeNGkzYks3Qk43Qmc/edit
A list of standard USB DAC reportedly interworking with the Android-powered smartphone Samsung Galaxy S4 having a microSD card slot:
stock Samsung Galaxy S4 > digital USB audio out >> USB OTG cable (ID pin grounded) >> USB DAC >> amp >>headphones
https://drive.google.com/file/d/0B3XYy1FuzDUeRHQwMjBJQ0VqSjg/edit
A list of standard USB DAC reportedly interworking with the Android-powered smartphone Samsung Galaxy Note3 having a microSD card slot:
stock Samsung Galaxy Note3 > digital USB audio out >> USB OTG cable (ID pin grounded) >> USB DAC >> amp >> headphones
https://drive.google.com/file/d/0B3XYy1FuzDUeQmhCNnRjZ1ZzRlU/edit
A list of standard USB DAC reportedly interworking with the Android-powered smartphone Samung Galaxy S5 having a microSD card slot:
stock Samsung Galaxy S5 > digital USB audio out >> USB OTG cable (ID pin grounded) >> USB DAC >> amp >>headphones
https://docs.google.com/file/d/0B3XYy1FuzDUeZDNBSVpjQU9Nd2s/edit?pli=1
A list of standard USB DAC reportedly interworking with the Android-powered smartphone Samsung Galaxy Note4 having a microSD card slot:
stock Samsung Galaxy Note4 > digital USB audio out >> USB OTG cable (ID pin grounded) >> USB DAC >> amp >> headphones
https://drive.google.com/file/d/0B3XYy1FuzDUeQ0ZnYlB5SzlWVWs/view
USB DAC descriptors:
https://docs.google.com/file/d/0B3XYy1FuzDUeZXNUYmF2SG5WNWs/edit?pli=1
The basics:
https://drive.google.com/file/d/0B3XYy1FuzDUeaTdfUjVYalRjcW8/edit
http://www.avsforum.com/forum/173-2...id-4-0-smartphone-tablet-10.html#post28879001
If you want the USB audio enabled on any Android device via official firmware/kernel, please vote (aka star) here:
http://code.google.com/p/android/issues/detail?id=24614
Star: Vote by clicking on the star (it appears after signing in)
According to Android 3.1 specifications, Android devices could support the USB audio feature, i.e. Android devices and USB_CLASS_AUDIO compliant devices like standard USB DAC could interoperate:
http://developer.android.com/guide/t...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).
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 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/
. 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.
FAQ:
https://drive.google.com/file/d/0B3XYy1FuzDUea3U3aTJ1RkpQdW8/edit
A list of USB OTG cables / adapters:
https://drive.google.com/file/d/0B3XYy1FuzDUeUFBGX05GTjU2UWc/edit
A list of USB Type-C cables / adapters:
https://drive.google.com/file/d/0B3XYy1FuzDUeWnh1XzRtdHpoRGs/view?pli=1
A list of stock Android-powered devices reportedly interworking with compatible USB DAC:
stock Android device > digital USB audio out >> USB DAC >> amp >> headphones
https://drive.google.com/file/d/0B3XYy1FuzDUeX2t4TmJRbVZsaVE/edit
A list of USB Audio Player PRO resources (compatible USB DAC, compatible Android devices, ...):
http://www.extreamsd.com/USBAudioRecorderPRO/
A list of standard USB DAC reportedly interworking with the Android-powered smartphone Samsung Galaxy S3 having a microSD card slot:
stock Samsung Galaxy S3 > digital USB audio out >> USB OTG cable (ID pin grounded) >> USB DAC >> amp >>headphones
https://docs.google.com/file/d/0B3XYy1FuzDUeRFIxNWE2eDZ6aE0/edit?pli=1
A list of standard USB DAC reportedly interworking with the Android-powered smartphone Samsung Galaxy Note2 having a microSD card slot:
stock Galaxy Note2 > digital USB audio out >> USB OTG cable (ID pin grounded) >> USB DAC >> amp >>headphones
https://drive.google.com/file/d/0B3XYy1FuzDUeNGkzYks3Qk43Qmc/edit
A list of standard USB DAC reportedly interworking with the Android-powered smartphone Samsung Galaxy S4 having a microSD card slot:
stock Samsung Galaxy S4 > digital USB audio out >> USB OTG cable (ID pin grounded) >> USB DAC >> amp >>headphones
https://drive.google.com/file/d/0B3XYy1FuzDUeRHQwMjBJQ0VqSjg/edit
A list of standard USB DAC reportedly interworking with the Android-powered smartphone Samsung Galaxy Note3 having a microSD card slot:
stock Samsung Galaxy Note3 > digital USB audio out >> USB OTG cable (ID pin grounded) >> USB DAC >> amp >> headphones
https://drive.google.com/file/d/0B3XYy1FuzDUeQmhCNnRjZ1ZzRlU/edit
A list of standard USB DAC reportedly interworking with the Android-powered smartphone Samung Galaxy S5 having a microSD card slot:
stock Samsung Galaxy S5 > digital USB audio out >> USB OTG cable (ID pin grounded) >> USB DAC >> amp >>headphones
https://docs.google.com/file/d/0B3XYy1FuzDUeZDNBSVpjQU9Nd2s/edit?pli=1
A list of standard USB DAC reportedly interworking with the Android-powered smartphone Samsung Galaxy Note4 having a microSD card slot:
stock Samsung Galaxy Note4 > digital USB audio out >> USB OTG cable (ID pin grounded) >> USB DAC >> amp >> headphones
https://drive.google.com/file/d/0B3XYy1FuzDUeQ0ZnYlB5SzlWVWs/view
USB DAC descriptors:
https://docs.google.com/file/d/0B3XYy1FuzDUeZXNUYmF2SG5WNWs/edit?pli=1
The basics:
https://drive.google.com/file/d/0B3XYy1FuzDUeaTdfUjVYalRjcW8/edit