Hiss, hum bad for speakers?


I've got some kind of hiss/hum going on here. Not sure if it is feedback from the high-level connection from my amp to my REL sub or just from connecting multiple amps into wall sockets. The question is, is this hum, hiss, high wine bad for my speakers and gear?
argent
Okay, after pulling out all the cables (and my hair) and redoing them, I have a theory. First, the hum has noticably decreased after reorganizing the wires. This led to an extensive removal and plugging in over every single cable, starting with the setup in straight 2ch audio and then growing the entire home theater around it. What I noticed was that that hum is always present, just quieter. The more connections I add, the louder it gets, until it is just barely audible from the listening position. Then, just out of curiousity, I changed the preamp setting from 2ch direct to dolby pro-logic. Walla, part of the high ringing (the annoying part) dissappeared. Now here is the disturbing part. I do not think that the pre-amp is truly "causing" the ring/hiss/hum. I think that during 2ch mode it is just so sensitive that it is picking up the darned video noise (it still broadcasts that stupid gray screen to the TV even in 2ch direct mode). Madrigal will be getting some irate-customer-email shortly, however, I don't think this is a fixable problem. The unit works fine. It just picks up the extra noise in the system. The unit is quieter during DVD movies, but if I pause the DVD I can actually hear the electonic cycling going on in the DVD player through the speakers until I hit play again. In all honesty, I am talking about a barely discernable noise that I cannot hear during music or movie listening. But after going from my 2ch only system where even the slightest noise was like a 3 alarm fire I guess I am a little picky. Thanks all for the advice.