Rotel 5 channel amp causes hum through speakers

I have a recently purchased Rotel 200 wpc home theater amp which is plugged into a dedicated circuit through a monster- power line conditioner. There is a low hum through all speakers, which are Thiel 2.2 mains & thiel scs center & rears. The center is mounted right above my samsung dlp tv. All plugs are grounded, and have line conditioners. Help?
I had a Rotel. I used a cheater plug. Thats a plug that turns a 3 prong plug into two. Available at Radio Shack and most hardware stores. Also experiment if you have Cable TV hooked up within your system. If so disconnect it to see if it goes away. If so thier are alternate remedies.
Had a similar problem which turned out to be the cable TV feed coming in my place. Once I placed a ground device on it, hum was gone.
Bypass the PLC and see what happens.
Make sure it isn't happening with you TV on only. I find the same thing with my Parasound amp. TV on, hum, TV off, no hum. Some after market PC's such as PS Audio's nicer ones have a removable ground pin. Also, Ernie M (Subaruguru) sells a PC that has a disconnect on the ground. You can then use a good quality PC rather than put a cheater in the mix. I suggest the cheater as a cheap way to check if this is a potential fix however.
Did you find the source of your problem? I have a low hum with my Rotel 5 channel, 200 watt amp. I have tried all the above, except the cheater plug, to no avail.

I tested the "little brother" to this amp--the 125 watt version--without a problem. Could the amount of additional power required to operate the bigger amp be part of the problem?

Please post if you've found a solution. I'm slowly being driven crazy by the alternating frustrations of hearing the hum and trying to eliminate it. Thanks.