Just wanted to thank you all. I solved the problem by lifting the ground on both amps. But a strange thing happened in the process. I plugged both amps into my PS audio Duet and didn't have hum but I got a muffled output from both amps even when plugged into separate banks. I unplugged one and plugged it into the wall socket and things were all good. I have a Furman pf 15 elite, so I decided to try both amps plugged into the high current outlet and this proved to be a great move. Absolute quiet. What gives with the Duet?
What gives with my Monarchy SM 70 pros?
I just recently purchased my second sm 70 so I could run them mono to drive my Usher be 718's. I am getting a loud hum in both channels. Has anybody had a similar problem and solved it? I might add that I am running them unbalanced.