Amp noise

[DRBOOM]

I was going to ask, what brand amp are you running. Most cases, cheaper amp have poor RCA grounds internally. I suggest you test your system with alternative amp to see if the system persists. If it does, then its poor head unit RCA grounding as well, ground the RCA s from the head unit by splicing speaker wire and doing a figure 8 around the RCA inputs of the unit, apply solder to keep the shape and ground the soldered wire to a head unit chassis. Try it again and see if it is rectified.