I still have this problem.

I have a Monster 3250 powering the fronts/center and an Onkyo 100X2 (don't have the model name off the top of my head) powering the rear.

Pop only comes from the fronts/center...

Edit - all electronics are plugged into a Monster Power Conditioner. There is a 'grounding bar' on the amp (might be on the conditioner...), but I'm not familiar with using this.