Fishing716: I just looked at the internals of your M6i amps on Google images and I must say for a 200wrms per channel amp the power supply does look a bit on the thin side to what I would like to see, esspecially the amount of storage caps. And a single dual winding transformer for such a high power rated amp should really two tranise of the same size. Suggest you try another amp to see if fixes your problem.
Cheers george
Cheers george