I just installed in after market in-dash cd player. The radio turns on, but I do not get any sound out of the speakers. Does anyone know if there is an internal factory amp somewhere on the car and how would I wire my radio to turn that amp on if there is on.

line level outs of the original radio. The rear amps had a 12V ON signal from the radio, to turn on the amp power. Many of the adapter harnesses sold for aftermarket radio installations in Audis are not configured correctly, neither for the rear line level out feed, nor the switched 12V signal to the amps and antenna RF amps.

Crutch field was telling me that there was a white wire that turns on the rear amp, but I don't see it, so right now I have the deck by passing the amp and I get front speakers. Crutchfield told me that I had to buy a 40 dollar pass filter of some kind, anyone hear anything about this.