Welcome JBrad,
Sounds like you may have a ground loop hum. Does it happen when only one amp is on? What other equipment is connected? Best to try and identify and eliminate the voltage differential at the source if possible and could be the cheapest solution as well. Test one component then one connection at a time then figure how best to deal with it. Why spend $120 on a CMX-2 when it may not be needed at all?
I had this issue a long time ago and it turned out to be my coaxial cable from my cable provider. With a
$2 cable ground part to my main house ground the issue was gone.
Cheers,
