Not many people realise but the later type CD changers for the Audi A6/A8/Q7 and some A4 can play MP3 disks, the simple way to find out would be to put a MP3 formatted disk in and see if the MMI/player picks it up.
However how do you tell if you in the market for one?
By part number, what we are looking for is the last 3 numbers on the sticker
111 = Non MP3
110 = Mp3 cd changer
I know what im looking out for on ebay cheap..