ooo good idea! I have cypress usb that we used to develop high end audio player, i think it has I2S and we already have audio driver for it I will ask my guy to see if we can hook up 2 things in oneThere are some I2S to USB converter around, not sure of the cost, probably expensive though. TAS1020B chips definately does I2S to USB. You can use 2 SPI's from your main MCU to rip the I2S stream and convert it to WAV, not hard to do but I guess it would be too much work just for a demo.
as to AM well i tell you that i dont even know how to use radio in my car, both FM and AM but i know all cards still use AM so when i look at CarPC i think it should have much more advanced features then regular cars so AM should be parts of it
To me AM and WB is just an emergency precautions, as ive seen NY after hurricane and when cell phones are not working, traffic lights are broken, trees are fallen you feel like it is a war zone and only way for me (2 years ago) to find out what happened was to listen to WB FM and AM was down too So after that I figured that before i through away my stock radio I need to get decent replacement candidate I was not able to find any decent existing solution so here we go ... doing this project ... probably will not brake even on financial side but at least will have nice toy