I dont know if this is in my last post but I tracked the loud pops in my stereo system to the front left rca output of my head unit(Eclipse cd 5000), imo anyways.

so I get this bright idea for lack of other resources to use only the rear two rca outputs of my head unit instead of all four.

I plugged these into my amp (PA500.4) , used the pass-through rca-outs of the amp then back into the remaining two amp channels.

I now do not have any loud pops but I have large changes in volume level on the left side

By the way this popping occurred before I replaced my amp which is why I think the head unit is the problem but I cant explain why adjusting the gain on this new amp causes similiar issues in volume

Am I grounding part of the signal when I adjust the gain at the amp?

Any thoughts appreciated