Noisy Onkyo 605...ground loop/RFI

[VinnAY]

Here's my problem: I have noise being generated by the 605 thru my speakers and sub. It's most noticeable on my PS3 because I normally have the volume in the top regions 80+/100. I know that I'm talking about a ground loop, possibly RFI interference.
I started addressing the problem in steps...
the PS3 I eliminated the third prong on the power cord, no improvement.
Unplugged the Coax cable from the STB, no improvement.
PLugged the PS3 via extension cord to the garage, no improvement.
Plugged the 605 via extension cord to the garage, no improvement.
Unplugged everything, one by one, PS3, ext HDD, HD-A30, TWC HD STB, no improvement each time I pulled a plug.
The 605 was all that was left plugged in and the noise was still there...it's a hum and static hiss.

So I've manipulated all the outlets, plugged and unplugged, etc.., I'm kind of at the end of my rope as far as the power connections. I have everything on the same outlet in a surge protector (the bargain bin type).

SO I'm thinking I want to go with a power line conditioner and surge surpression unit, with coax inputs, etc..,


Do you guys have any thoughts if this would be effective on this problem? MonsterCable seems to have something in my price range the MP HTS800, I have to contemplate some overpriced Monster gear....

Suggestions? PLEASE!?!?!


Edit:
My Gear
Samsung 56" DLP HLS-5687W
Onkyo 605
HD-A30
TWC HD 8300HDC set top box
PS3
External HDD (for the set to box, DVR expansion)
JBL speakers throughout