Urgggg ground noise........

Got this low level hmmm coming from my tweater only,the mid and base is barely noticable,so Im assuming the ground problem is in the higher cycle range...is this a common occurance that ground loops only affects certain freqencies?...also by floating the ground with a cheater plug do I plug the cheater plug directly into the wall outlet or can I plug the cheater plug into the conditioner?..
I found one of the causes,its was definitely the flat screen TV adding the buzzing hash,when the TV was completely unpluged the buzzing went down to a "acceptable" level from a "unbearable level"..now Im going to buy a floater plug(cheater plug) and see if I can get a fresh line...is it true even if the TV is unplugged it can still cause ground problems?.....
I installed a Furman RI-1220 balanced power conditioner
in my system and it made a substantial improvement in
lowering the noise floor and giving greater transparency
and detail. A number of companies make balanced power
conditioners. They aren't cheap, but they offer many
benefits including elimination of grounding problems.