I had one sunfire amp the TGA 5200 and everything was running smoothly.
Now that I added a 2nd amp a Sunfire Grand Signature series my sub is doing a noice even when the amps are turned off.

I have every thing going through a Panamax surge/clean protector.

When the receiver and the amps are turned off I still hear the sound through one of the sub. The sound is not that loud, but when I put my ear next to the sub I can hear it. This noice was not there before so I imagine it has some ground or how ever you say that.

Can any one tell me how to fix this

Thanks