Thanks estocks. I still have noise and here’s what I have:

It’s a 4 ch amp with no bridge and four Infinity Kappa component speakers. I’ve run 12 gauge wire to the speakers and there is no chassis grounding on the speaker wires. The + power cable is 4 gauge copper. The ground wire is a very short 4 gauge copper wire grounding to the floor pan.

With no input connecter and all, and the sub amp disconnected as well, I still get noise through the speakers. I’ve tried powering the amp with a different battery totally disconnected from the car and sitting right next to the amp. This was even noisier than when it was connected to the car battery.

The only other option I see is that the noise is coming from the speaker wires. I’ve read that that is not usually the case. The only thing I can think to try is to hook up separate speakers to see if the noise goes away. Maybe I’ll first try disconnecting the front speakers as they run next to some of the cars wiring.