Floating the grounds means that the equipment ground is no longer tied to the outlet receptacle ground like using cheater plugs. Ground loop happens when the ground that one equipment is using is at a different potential from another piece of equipment. A small current loop is created when the resistances of the two grounds are slightly different. It has nothing to do with the quality of the equipment or the power supply. The last time I had a ground loop issue was with the cable TV coming into the house that had a different grounding source from the house ground. I solve the problem by isolate the cable ground from the house ground. This does not always work with all cable systems. Some RCA cables avoid the issue by connected the ground only on one side of the cable. It is best to have a good single-point grounding system than to lift or “float” the ground from a safety standpoint and to reduce interference from other sources like RF.
Edited by john57 - 7/5/12 at 3:04pm