We have a new theater system. What is causing our speakers to hum? Is it the TV, receiver, speakers or?

Question

the cable company? Is there any reason why one or any one of these devices shouldn't work properly or be incompatible with one another?

Answer 1

It could be as simple as signal wires being to close to power cables for the equipment.  Try moving cables around and keeping signal away from power.  If you have to cross them, do so at a ninety degree angle if possible.  

Did you have the theater system installed?  If the installation was extensive and they had to run wires in the wall, the wires could be picking up electromagnetic interference from something else in the house.  Does the hum only occur when the dishwasher or the compressor in the refrigerator runs?

Chances are, placement of wiring is your problem.  Check all these possibilities before you try swapping equipment.  Good luck.

Answer 2

I answered this question in your other post.

The cable company should not have anything to do with your humming. Read the answers on your other post.

Answer 3

ground loop (check all wiring jacks , a/c plugs and a/c recepticle make sure it is grounded try switching replacing all wires one at a time if you have any iec(removable a/c wires switch them as well