Lifting the Ground

Do you have hum problems?

Is it recommended that I use a cheater plug on any or all of the three units? I have my solid state amp going into a second wall outlet. Is it recommended that I also use a cheater plug on the amp

Recommended, surley not by the manufacture.
=================

I don't want to come back from work and find my house burned down.

No that will not happen. What could happen if an internal ac fault or leakage were to occur in a piece of equipmemt from the hot conductor, be it a wire or a winding in a power transformer to the chassis or case, the case could become hot with repected to any other earth grounded equipment. A small leakage of current would, should, be bled off by the ics to a piece of equipment that is earth ground connected. If you do have to use ground cheaters because of ground loop hum problems and you cannot solve the problem, make sure to unplug all equipment using ground cheaters before disconnecting, or changing out ics. If a leakage is present you could receive an electrical shock.

"Recommended, surely not by the manufacturer"

Well, actually, the 500w subwoofer amp from Hsu Research (Model #500A)comes packed with a cheater plug, with the owner's manual saying that you should use it with the amp if you experience a hum problem. I did, and I did. Dave

Lifting the ground is used to cure hum problems.
Maybe a few golden eared ones have discovered some other use for it but not to my knowledge.
Polarity and ground are the AC hum-busting tools.
The other big hum creator is cable TV service lines.
Then you got radiated power fields from local AC lines/generators and motors, florescent lighting..
IMO worrying about lifting grounds without hum present is not worth the bother.