My 1996 A6 is fitted with top of range radio and 6 disc in boot however rear door speakers will not work only the tweeters do someone told me that the main rears have a separate amp built into speaker housing however as both sides dont work and yes i have moved the balance on the radio! It i should think have a live feed to speaker assy to feed amps there r five wires on the plug! anyone have any suggs just had cambelt and stat car V6 2.6 nice reasonable quick car

 

I had the same issue in my '96. If you are running a Bose system (the fact system) then each speaker does indeed have it's own amp. Mine just had an annoying crackling sound in my rear driver's side speaker and rear driver's side passenger door. Since I didn't and don't have the cash to get it fixed, I simply disconnected the speakers from the Bose amp in the trunk. It sounds s like you need to replace your speaker amps. If you run a live feed to the speakers, you'll blow them. I asked around at a few car audio shops and this seems to be a problem in Audi's, Lexus' and any other car that has a stock Bose system.
Good Luck.