Cheater plugs with amplifiers?

Thanks, I get it. One for power and one for signal. I also have never had the chassis of any gear become "hot" and have used some pretty ancient, though well maintained (by professionals) tube gear in the past. Though, I did have a close call with a Hafler 500 power amp that I purchased used and owned for a short period of time. When I was checking out the internals after purchase I discovered a cracked connection on the integral power cord that could have shorted from tension on the cord in time, and since it was being used as a PA amp and being moved around a lot, Murphy's law probably would have prevailed. Fortunately it just required re-soldering.

Jab, reverseing the plug will not help this gentleman with his problem. The problem has to do with ground loops. Ground in this case has a little extra resistance through which some parasitic currents are flowing which is inducing a voltage. Floating the unit gets rid of the noise but at some safety risk.

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.