I got one of these and it works well. I do not use the USB, however. I do use the hands free phone and I stream music from my phone. I do have a problem with space behind the Symphony 2 full Bose system, head unit, though, can’t get it fully back in. I need to find a way to rout the cable out of that space and tuck it up behind the glove box, or something.
Bluetooth Handsfree A2DP CD Changer adapter for Audi A2 A3 A4 S4 TT 1998-06