Some amp makers suggest the use of (1) cheater plug on just one of the monoamps. A good way to tie the two monos together is with a heavy duty 1 to 3 a/c outlet adapter cord. Home Depot has a nice 12ga pigtail type. Using one of those you can plug in both amps on one wall outlet. Sometimes it takes alot of experimenting with different powercord positioning. Get an extension cord and plug the preamp into another outlet on a different circuit and listen for change. It can be other things also but moving the preamp to another circuit works alot of the time. Good Luck.
What makes an amp hum/ground loop?
I just hooked up a pair of monoblocks in place of a Coda stereo amp. Nothing changed. I am and was, running directly out of a cd player with an analog o/p. When I hooked up the m-blocks, I got a hum in my speakers. It only happens when BOTH monos are hooked up to the cd player. But that was no problem going into the Coda. Suggestions anyone? Thanks!