If you want the USB audio enabled via official firmware/kernel, please vote (i.e. request to Google) here:
Issue 24614 - android - Enable USB audio on the Galaxy Nexus (or any Android 4.0 device) - Android - An Open Handset Alliance Project - Google Project Hosting
Star: Vote for this issue and get email change notifications
Star: Starred by 3056 users
About USB audio
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, a Galaxy Nexus is a digital audio system.
Hopefully, the Galaxy Nexus, 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.
Issue 24614 - android - Enable USB audio on the Galaxy Nexus (or any Android 4.0 device) - Android - An Open Handset Alliance Project - Google Project Hosting
Star: Vote for this issue and get email change notifications
Star: Starred by 3056 users
About USB audio
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, a Galaxy Nexus is a digital audio system.

Hopefully, the Galaxy Nexus, 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.
