Quality Cheater plug??

I simply lifted the ground inside the outlet... it's the green wire. Proceed at your own risk. ... and turn off the braker beforehand to kill the power to that ckt.!!

My exp? Done it for years with no probs... usually it stems from the cable/satellite/phone ground at the servidce pole outside your house.

There are filters too which can help if in an apt. However some of these filters can affect the speed of the cable box' when going form ch to ch and so forth.

I've not seen a cryo'd cheater or the like yet.

I had a similar problem regarding hum with my setup. I went from a dead quiet house to a problem when I moved here to Arizona with the left speaker humming. My speakers have amps in them. When I talked to Richard Vandersteen, he advised me to run a ground wire from the humming speaker amp to the main amp or preamp which quieted the problem. It seems that the speakers were on a different circuit than the other electronics which created the different ground potential. Try running a very thin wire touching different components and see if it works. In any case, using a cheater will ruin the sound..grainy, no depth, etc.

It's permanent but cut off the ground.

Someone posted the following on Audiogon a short while back on this very subject. It's worth a read prior to un-grounding your system.

http://www.aes.org/sections/pnw/pnwrecaps/2005/whitlock/whitlock_pnw05.pdf

You, probably, are getting a ground loop through the outlet.
You might try plugging into an outlet on a different circuit, that could solve your problem.
Or, conversely, you could unplug each thing in the house on that same circuit, one by one, and see if and when the hum stops. Then, you've found your culprit. And, then, you could try plugging THAT into an outlet on a different circuit.
If the above fails, or, is simply not possible, or practical, you could buy an Acoustic Revive RGC-24 Grounding Conditioner from VH Audio for $449.00 and that would, probably, solve your problem--safely (and improve your system's sound quality). If you were to try that, I'd suggest emailing Chris, first, to ask him what he thinks.
Barring all else, disconnecting the green ground wire from the outlet, as has been suggested would, likely, eliminate the hum. But, it does pose potential hazards.
The easiest solution is to just take some bolt cutters and chop the ground plug off your power cord. That would facilitate obtaining correct AC orientation, as well, since you could try the cord flipped each way and pick the one that sounds best.