I just finished installing my amps in my 02 GMC. Of course, I got the dreaded buzz when the key is in run or the engine is on (buzz also changes with RPM). Funny thing is that the system is crystal clear when the ignition is set to accessory.

Could this still be a ground loop. I had the amps grounded by the jack mount, but noticed it sits on carpet. I am going run a bolt straight through the floor and mount the grounds directly on the body. I may even run a ground strap from the end of the bolt protruding through the vehicle directly to the frame.

With the RCA's unplugged and the amps powered up no noise. I am guessing it is trying to ground through the RCA's.

Any advice is greatly appreciated.

Note: I am definately running twisted pair RCA's and quality power cables (separate from signal lines). When the head unit was running the speakers, no noise. Only after amping did I get the noise (only through amped speakers).

Hopefully, the new amp ground works.