Sounds like a ground loop hum. Break the ground in one of the amps. If there isn't a switch on the amp for it just replace the power cord with one that doesn't have a grounding prong.
Clayton Amp owners - do you have a hum?
Greetings ... I run Clayton Audio M70 monoblocks and have always been aware of what I assume to be a transformer hum. I recently moved the system to a new dedicated room, and now the monos each have their own dedicated 20 amp circuit, wired with 10-2 w/gr. MC cable, and VD duplexes. Previously, the amps were part of a "makeshift" 2 ch./Ht setup, and I always thought the hum was attributable to less than ideal house ac and equipment positioning. But unfortunately the hum has accompanied them to their new and better environs. The only thing I have tried to this point is to drop their grounds w/ cheater plugs, and I couldn't tell any difference. The hum does not emanate from the speakers, and it's weird to describe, but it is very hard to localize by placing one's ears right up to the amps - it's more of a background presence. It has been suggested that I try a BPT conditioner, but I really can't afford the price of admission at this time, and to be honest, I really thought the dedicated power lines would have eliminated it. I have used Shunyata Black Mambas on the amps from the start- come to think of it, I've never even tried the stock pc's - probably would make sense to do so, for a reference point (duh!) So, just wondering if if any other Clayton owners have experienced the same? Thanks...