*update*

I went behind the cable box and unplugged the cable cord. This reduces slightly the hiss, but something is still there. So I unplugged the component video cables that went from the cable box to the 990. This alone reduced about 70% of the problem. The cable box remained to be plugged in to the 990 via the optical cable, but removing this did nothing to the hiss.
Next, I went to the outlaw cables and some monster ones. I use Outlaws PCA cables on all speakers except the sub, which uses a thick monster Cable. I have to use a Monster set of y adapters for the bi-amping of the LSi15's and Outlaw doesn't make their own brand of Y-splitter. I discovered that the Monster, like the Outlaw PCA's is designed to be plugged directionally which means arrows indicate the flow of the signal. I discovered that this was put in wrong initially. Just unplugging everything eventually got the noises to stop. It's interesting, even with the fronts PCA's disconnected, the 7500 is still sending some signal, and depending on where you put the PCA's (to lay down) you can get quite a bit of noise. I then plugged everything back in except for the Cable component and the cable into the back of the comcast cable box. The hiss was reduced greatly. So I have linked 70 or 80% to the cable box.

BUT, I got to thinking as I was unplugging the Outlaw PCA's from the back of the 990 (both Outlaw products). You see, the cables are quite heavy and since the are likely to dangle downward, the apply quite a lot of pressure on the output jacks of the 990. Are these output (RCA looking) jacks on the 990 at risk of becoming part of the problem themselves? I say this because even when all of the cable cords were removed from the 990, if you were to use your hand and grip the audio chords exiting the 990, you could hear QUITE a noticeable distortion. Call me paranoid, but thatr doesn't seem right.

thoughts?

I've always heard "noise" from speakers when moving around cables with components turned on - others here with a better EE background could offer a specific explanation, but I've run into it with every component I've ever had. Technically, I suspect the recommendation would be to turn everything off when switching cables around and then turn things back on, although practically you're not likely to hurt anything by moving cables around when things are on.

By the way, have you come across this link ?

hell's bells, I guess Outlaw does make them. But they don't make a PCB version.