I have the standard ground loop hum problem in my home theater since adding CABLE to my setup. With the cable box turned on, when I attach the coax, I get a 60 cycle hum in all my speakers, even with the volume turned all the way down. When I disconnect the coax, or simply turn off the cable box, the hum goes away. http://www.dplay.com/tutorial/cablehum.html#atten I performed the tweak with the 75-300ohm transformers as shown on that site, which completely removed the ground loop hum...>HOWEVER< this reduced my signal too much and made my HDTV channels unavailable, so this is not an effective solution, nor would a -6db attenuator, for the same reasons. I installed a -3db attenuator on the coax, and this reduced the amplitutude of the hum, but did not totally remove it from the signal path. So....HELP! I'm not sure what else I can do, but with speakers everywhere and a big subwoofer in the corner, the 60hz hum is quite distracting!