Instead of cheater plugs, which may degrade the sound, I have, in the past, disconnected the grounds in each of my dedicated outlets. I realize the potential hazard of doing this, but this did eliminate hum in a previous system. Today I ground my amps, but have the ground lifted on the outlets that the preamp and source components are plugged into. All neutral and safty grounds are star grounded to a dedicated grounding rod which is also connected to the house's main ground. This set up is quiet, and while I can't be absolutely certain, I believe that I am protected as well.
