Ive just tried to fit a kenwood cd player in my 2001 a3 (non bose rear amplified) using the pc9-404 adapter. Stereo works but still only the front speakers have sound.
There is a couple of wires not connected i.e. 1 red connector block with 1 wire going into it, 1 wire with spade connector that went to the factory headunit, and a blue and white wire coming from the same connector as the RCA leads.
I will put some pictures up tomorrow
any ideas would be much appreciated, cheers