i do have the cables close to a power source and i also have the 7500 running on its OWN 20 AMP line.

remember, the 7500 was biamping the LSi15's (fronts). I decided to switch the upper drivers on one of them to be driven by the 2200 which had been driving the rears. Everything is on a component rack and I use the holes in the back to snake the cables through. When I made the switch, the hum was gone from that particular speaker's tweeter and replaced with a slightly more acceptable his. At this point the only thing left to test would be the brand new AudioQuest Type II speaker cables but I doubt there is any problem there. My fear is that something is slightly amiss with the 7500. I am also going to try routing the 7500's power cable away from the interconnects with which it share a hole.

well, with the help of tech support, i was able to narrow it down to the cable box. Now I am really in a pickle. disconnect the coaxial cable and the hum is gone as just a nice peaceful very soft hiss is present.

Ah, the joys of a ground loop from your cable service. Classic problem. Fortunately, there are good ground loop isolators out there that can fix the problem without requiring you to try to convince your cable service to fix their grounding. I've heard that the Jensen isolator is the most effective out there (isolates without killing signal strength), although it's pricier than other alternatives available from places like Parts Express.

Can ground loop problems also become present if you are using a satellite? I have both cable and sat. in my house but only satellite going to my H/T room.

Yes, I have heard of grounding problems with satellite connections. I haven't ever had satellite, though, so my experience is nil.

where can I look to get these devices Gonk, and how will I know they will work with my Comcast cable box?

Here's one source for the Jensen I\'ve heard folks say good things about . There's also one from Parts Express and one Xantech unit from Home Tech . Any of them should help with problems in a cable service (which box being used shouldn't matter since it's related to the signal itself), although I don't know if any of these are supposed to be used with satellite service.

Most splitters have a screw on the side where you can run a bare piece of copper wire from to your house electrical ground, (ground rod, copper pipe suppling your water). This should clear up most ground loop problems, and it's cheaper too!. Jim

i did that and nothing happened. The weird thing is that there is NO hum or hiss in the surrounds which are also connected to the system. I am not blaming the 7500 (the 2200's power the surrounds) but you would think that the ground loop problem would be heard in the surrounds as well. As for the outlets and what is connected to what I have a BIG Monster Surge Protector and line conditioner. That is plugged into a regular 15 amp outlet. These are connected to this Monster powerstrip: LCD TV, cable box, DVD player, both 2200's (using the two "high current" plugs on the power surge protector). Also the SVS sub is NOT connected to the surge protector but it share the same circuit with it. The 7500 amp runs on its own 20 amp outlet that I installed (yes, I did a good job with the right guage wire) but the computer's PSU is also run off of this 20 amp outlet (even with the computer off the hiss is present). It may be important to note that from the 20 amp to the component rack, it has quite a ways to travel . . . on a cable unfortunately designed for 15 amps. I will try to provide a picture later.