RAK said:
Well, I was the house audio engineer for a 1200 seat theater, that certainly would have made things interesting. haha. But we usually used iso-transformers for power issues if they came up. It was usually the rentals coming in that had noise in their systems and tried to blame it on us.
As an example, what about plugging in a guitar amp into an AC lift and then plugging that into a quad box or something like that, isn't that a useful application for it? (assuming you think there's ground loop noise coming out of the amp) Am I way off base here?
Also, I have the KRK RP8s and have been very pleased with them.
It's always the outside gear that causes the problems

. I feel your pain. I've spent a lot of time making sure my system is right, and learning how to interface whatever pieces of shit come through the door without noise. Real PITA sometimes, especially when signal ground lifts refuse to work.
The thing to realize is that those little 3-2 dealies are NOT ground lifts. They have a ground connector that is supposed to be hooked to ground with the center screw in the outlet, which is supposed to be grounded. That way you can plug a three-prong plug which needs that connection to be safe into a two-prong outlet.
There is always a solution which doesn't involve lifting the AC safety ground. Iso transformers or DI's with ground lifts. Better cables. Better/redesigned gear. And so on. All things that don't kill.
You might be able to be safer if a GFI is used with a ground lift, but I don't know if it's legal to lift a safety ground and use a GFI instead. I would doubt it, though. And GFIs have their own hassles.
So, to recap, those 3-2 things are:
Dangerous if not hooked up right
Void warranties if not hooked up right
Illegal if used to lift the safety ground- that means you and your business in trouble if something goes wrong.