Do you have cable TV connected to it? If you do, disconnect and see if it goes away. If it does, search past threads on how to corect this problem.
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If you have 3 pronged plugs, get enough two prong adaptors and "float" the ground, though it will probably just be the amp that will need floating. If the problem goes away, you need to call your electrician and have him get you better grounding unless you want to keep the ground floated, which is not a real good idea. At the moment it sounds like one piece of gear is not getting good ground. But hey, I could be wrong.
Along the lines of Jvia, perhaps your system has a ground loop caused by more than one three-prong AC main cord. Since individual components are connected to each other through their interconnects (and you say when you remove interconnects the hum stops), only ONE component should be three wire connected to the AC receptacle or line conditioner. All other components should be two-wire connected only. I purchased some two-prong ground adapters from Radio Shack and attached them to 2 of the 3 three-prong plugs in my system and eliminated the ground loop and corresponding hum. Of course this will only help in your case if you have more than one three-prong plug in your system. Good hunting otherwise.
Try disconnecting the tv-cable and unplugging the tv. If this eliminate your hum, then you can fix this cable ground loop hum several ways without costing you any money.
Either ensure that all grounds to all components are using the same ground and/or circuit.
Or disconnect the ground (for safety sake many will discourage doing this) at all outlets for your tv and audio components.
Check what Herman says above....most cable TV feeds into your home will ground the cable to the same earth ground(pipe) that the AC input to your home is grounded to. Many cable TV feeds have serious DC voltage on the ground, and thus my be placing a DC voltage on the ground pin of all of your homes AC plugs...causing hum/noise on your system...let alone reducing the overall capibility of your components.
There are quite a few threads that deal with this issue and take you through a step by step diagnosis to help isolate the cause. You may want to do a search on 'hum'.
I would first disconnect the tv cable and see if there is any change. If the hum goes away or is diminished then you need to isolate the cable tv ground from your system. A cheap and very effective way to do this is to buy a 75ohm to 300ohm cable converter and a 300ohm to 75ohm cable converter. Chain them together (75ohm->300ohm => 300ohm->75ohm) and hook up the 75ohm connection of the 300ohm to 75ohm converter to your tv or cable box. Hook your cable tv up to the 75ohm input of the 75ohm to 300ohm converter. These parts can be bought at RS for around 6$.
Just one other note, I briefly owned a Parasound 2003, and currently own a Parasound 2205. I've had serious ground loop hum problems with both amps and have resorted to lifting the ground in each case. Good luck.
If you haven't figured this out yet... I noticed you said the equipment is on "circuits". This being the case, you may want to temporarily connect everything piece by piece into a single outlet (single circuit). This can be accomplished by using a cheap power strip, 6 into 2 outlet adapter, etc. Sometimes if you have 2 circuits, the grounds are tied at the breaker panel, which can create a ground circuit loop the length of 2 wiring runs to the breaker panel. If you find this is the issue, you may have to connect the grounds at the outlets to get a common ground point for your stereo.
The other excellent points above are to search on Hum, or remove any connections to cable TV for TS purposes. You may also mail me with questions, as I know HUM problems pretty well...
Ground breakers are fine if you live in a rural area, or do not have sensitive video equipment... I used to use the ground breaker until I got a big screen.... What happens in an urban area, you will get other noise problems with a ground breaker unless the distance of cable after the ground breaker is less than the length of 1/4 wave antenna. With my setup, There was no option other than to fix the issue... Yes - 2 weekends of troubleshooting and refurbishing grounds everywhere that mattered... Now my system is dead silent on the audio & perfect on the video.