well the common theme between grimster and knownalien is they are both running the 990, and one of the Outlaw Audio amps..

maybe the amp needs a better grounding? Maybe it needs it's own wall plug in? Or a cheater plug.

I have the same 990, but not any Outlaw Audio amps.. and no buzz. I just throwing this out as a similarity between those two people, with very similar problems.

do either of you have differnt amps? DOesn't matter if it's a 2 channel or not. try bypassing the Outlaw Audio amp and see what the results are.