I GOT MY EMPEG INSTALLED!! It wasn’t too difficult. I will post the pictures on Riocar.org soon. I think I know where some people with Audi TTs went wrong and got the dreaded alternator whine.
There are 4 line level inputs to the bose amp and one common ground (so 5 wires in total). I had to chop up an RCA patch cord and splice it to the Audi harness to utilize the existing BOSE amps. It would be nice if someone manufactured a harness for this – I couldn’t find one. If you only do the front inputs you get sound from all 4 speakers, but a terrible alternator like whining sound (even with the car off). Once I hooked up the rears, sounds great.
The confusing part is there are 8 speakers (4 fronts, a front center, 2 rear, and a 9' sub). The rears are hooked up mono. The sub is dual voice coil and the center is wired to the fronts in parallel. How BOSE gets from 4 inputs to 8 channels is still somewhat of a mystery to me.
I wish the gain was a bit higher on the BOSE amps, but its perfect if you are using Tony’s method of adjusting the gain (0db is as load as I would ever want to go). The BOSE system needs some more bass and treble in the EQ than my previous car.
Getting everything (including a tuner) into the dash was a tight fit. I would say this was one of the trickiest parts to the install. There is room down behind the climate control system. I was just able to get it in far enough to close the stereo cover.