I think I have tried it once before with the wire. I think I tried it from the sled to the ignition lock. And I think I checked for loose wires when I installed the GPS. That's when I installed the amp and ran the other HU through the Empeg instead of running the Empeg through the HU and using it's built-in amp. That's also when I got the alternator whine. Didn't have it before I used the external amp. When I used the amp in another install in my first car, I didn't have any alternator whine either, but it is about 10 years ago, so it could be that some caps in the amp has dried out and that's why I get the noise now... I guess I could borrow another amp and see if I have the noise with it, too. Decisions, decisions...

Anyway, thanks for the help and suggestions.

Stig