Quote:
We may develop a new portable DAC for all Android phone , some different with our E17/E7,
2, maybe only support up to 48k/16bit if the phone can only output such format
Android 4.0 Ice Cream Sandwich includes the USB Audio Driver for ALSA which can be compliant with USB Audio Class 2 (UAC 2) devices allowing for 24 bits / 192 kHz among others.
http://thewelltemperedcomputer.com/HW/USB_Audio.htm
https://bitbucket.org/franciscofranco/android-tuna-omap/src/388ae9aa9b26/sound/usb/Makefile
"The newer versions of ALSA (the Advanced Linux Sound Architecture) enable software mixing by default. All sounds which are played are converted to 48kHz (by default) and mixed in software.
There are a number of solutions to this problem."
http://www.hydrogenaudio.org/forums/index.php?showtopic=47591
"Bit Perfect Audio
You need to be aware that ALSA by default will upsample all of your audio to 48 kHz. This keeps it compatible with TV broadcasts as well as Dolby Digital and DTS surround on DVDs. ALSA typically takes the sound from your content, routes it through a module called "plug" where this resampling takes place, and then routes it to a module called "dmix", a software mixer, before it outputs it to your SPDIF/iec958 connector.
For Die hard Audiophiles, this resampling is a real source of irritation as CD audio is made using PCM at 44.1 kHz. The upsampling in ALSA is unfortunately very low quality, and if you have a half decent amplifier and speakers, you will notice that CD playback has a congested compressed sound to it. This is very easy to overcome"
http://www.mythtv.org/wiki/Bit_Perfect_Digital_Audio_Playback#Bit_Perfect_Audio
Enable USB audio on the Linux powered Squeezebox Touch interworking with asynchronous USB DAC:
http://www.digitalaudioreview.net.au/index.php/news-blog-and-showcase/john-darkos-blog/item/150-how-to-enable-usb-audio-output-on-the-squeezebox-touch
"UAC 2 support
Based on Mark's feedback [using an async ARCAM DAC] I've updated the Usb Audio Output applet to version 0.6. This should now support detection and selection of dacs wanting 32bit samples. This is working for Mark with kernel #4 to support uac 2 dacs."
http://forums.slimdevices.com/showthread.php?93310-Async-USB-Dac-Experiments-testers-wanted&p=696152&viewfull=1#post696152