[Q] What is the state of external audio input on Android?

Hello,
I'm trying to get higher quality audio input (sample width and conditioning, don't care about sampling rate above 32k) than is available through the microphone jack and was looking for an overview of where the development of such capabilites stands today. From what I gather:

• Android 3.1 (maybe 3.2) added some support for USB Audio, though I can find almost no details on the capabilities. I can't post links, but a post on computeraudiophile with google search terms "usb audio enabled galaxy s3" claims support for a bunch of USB DACs on the Galaxy S3, but there is no mention of using the ADC.
• Android 4.1 added support for USB audio docks -- these are generally (as far as I can find) speaker systems with a USB cable -- which only support audio output.
• Software such as USB Audio Recorder Pro can record from a number of devices but this is of no use to a developer wishing to get the data into a separate application.
• Lots of devices have HDMI ports but I found nothing about anyone managing HDMI input.
• I can't find any such device for Bluetooth, but also nothing suggesting that it isn't possible. If so, can anyone speculate on audio quality limitations?

Now, I understand that the vast majority of users who want USB audio want output so it can go to their speakers, but there are some who need the other direction (or both...). Can anyone more familiar with the subject comment on the state of external audio input on Android devices?
Thanks,
Ben