Audio Systems: loud pop when sound cut, clarion head, pioneer speakers

Question
Hello. Equipment: Alpine MRP-F450 amplifier, Pioneer speakers, Clarion head unit. I now get a very loud "pop" when I change tracks on a CD, switch sources, or turn the volume to zero, anything that totally cuts power to the speakers. The "pop" is definetly originating from the speakers themselves. The rear speakers, which are not hooked to the amplifier, do it as well.
When power is suddenly cut to the amplifier (remote turn on wired through switch), the "pop" does not occur. I've checked all grounds and they are good.

Any suggestions? Thank you.

Answer
Hi Zach,
Answered your own question really, "When power is suddenly cut to the amplifier (remote turn on wired through switch), the "pop" does not occur"
So it must be head unit related.

Have you tried it with the amp off and turning the volume down? Do the rear still do it?
Just for the heck of it, have you tried to connect the remote switching from the head unit instead of by a switch?

I don't advocate a switch as they can be forgotten and the amp left powered up draining the battery, not so bad if using a Split Charge Relay, but a dead car is no fun.