Just in case others trip across this, I figured I'd explain the Android thing a little bit. Right now there are two ways to use USB DACs with Android:
- Build an application to run a parallel stack (like USB Audio Player Pro) to the Android audio API
- Build the support directly into your image (pseudo-fork) of Android for your device
USB Audio Player Pro works on all of my Android devices, but it doesn't really care for the .PLA playlist files that MC20 defaults to when connecting the Android device to sync with. It does, however, work beautifully with my Nexus 7 and Galaxy Note 3, among many other devices. I believe this application still requires USB OTG support hooks compiled within the kernel (think "drivers") into the OS, which is why earlier devices were more miss than hit with it. HTC and Samsung had this support built-in for at least a couple generations of devices, probably for docks or tied into using MHL/microUSB connections. I was able to use my Native Instruments Komplete Audio 6 USB I/O box with my Nexus 7 using the "USB Audio Recorder" application (same dev, but this was the first application for use with a DAW they made as a field recorder).
The use of an outboard USB DAC/Amp is rather annoying, but if you have good source files, gear (including headphones), and range of hearing left ;-) the difference is huge. It's much more readily apparent if you produce your own music in the 24-bit/48 kHz (or better) domain as the stock hardware usually can't deliver the power AND S/N ratio at the same time to support everything it can deliver. Hopefully with the new code base, we'll see more vendors make it easier to get higher resolution files to play natively (including AIFF) and we can move forward.