[Riveted1]

You're gonna have to go through and try to narrow down where the problem is. I would start with unhooking the amps from the head unit and hooking some speakers to the powered outputs. If you have pops there, then you know the problem is between the head unit and the air setup. If you don't have pops, then it is between the amp (or amps) and the air setup.
Since it pops no matter which valve is opening/closing, it seems like the problem is elsewhere, but if it's a grounding problem, those can be wacky! It could also be as simple as a cheap RCA cable being crossed by a power wire to the air setup.


So, you have homework to do!