Wanted to share what we did for Mafisto's car to get it going correctly. He'll have to show up here and help out, but hopefully this will prove useful down the road when someone does a search...

We went ALL OVER town to find an adapter to plug into his stock harness and found nothing. Several shops swore that we had to rewire the whole car, that was how they've done it several times already and was the only solution. We knew this was moronic and told them so. We found an Autoleads adapter, mailed from the UK by Andy (thanks!) from his former TT installation. Mafisto will have to provide the part number. They also make some small plastic tabs to cover the gap on each side of the player. It'd be up to the next TT installer to figure out how to get those adapters shipped across the ocean - but they do exist!

Attaching the adapter was fairly easy, but there were a few problems... 1) TONS of ground loop noise out of the system, and 2) no sound from the rear speakers. The ground loop problem was solved by a simple "ground loop isolator" from Crutchfield. Again, Mafisto - part number and price? Very straightforward, simple to plug in and use, a true 5 second job. It took care of the whine, for a while... the lack of sound from the rear speakers was due to the Autoleads harness having only 1 pair of RCA's on it, for the front speakers.

Solving the problem of the rear speakers, we fabricated two additional RCA cords from a spare A/V wire. Stripped the inner and outer shields back, and soldered both shieldes to the same place on the harness as the original RCA shields were soldered to. Next we had to fabricate to new pins to fit into the Autoleads harness. A Metra VW harness (Note VW harnesses do not work in all Audi's) was yanked apart for donor pins, and the tail ends were soldered to our new RCA leads. We pushed these pins into the Autoleads piece (refer to the wiring diagram on the stock head unit to see where they go). There was a little fabrication to make everything fit into place, but a simple pair of snippers solved it.

A little bit of heat shrink tube and some zip-ties later, we were finished.

Of course once the rear RCA's were hooked up, we basically reconnected the ground loop. He'll be ordering another ground loop isolator, and we fully expect the noise to go away again.

Sorry for the incoherent write-up on this, just wanted to provide some info for the next poor unlucky SOB facing a factory Audi installation. We did a good job with the adapters and harness, no Empeg or Audi wire was touched during this installation. We band-aided the ground loop problem, but it was an easy solution and it does work perfectly well. It finally works! Needs some EQ tuning though

I'll try to get a few pictures when the second isolator goes in. It isn't pretty, but it's secure, and it does work!