Floating the Ground

I can't offer a lot of help beyond what John has suggested, but I do have one thought: try installing the ground loop isolator (GLI) that Radio Shack sells before you spend $100 on the Mondial unit. My son had a hum problem similar to the one you describe, which we determined was caused by the input from the TV to the pre/pro. The Rat Shack GLI eliminated the hum when it was installed -- and I think it cost less than $20.

I had that problem too and a ground loop breaker fixed that. Now the problem starts and stops when I plug in the REf. 30. Like I said, I think there is a problem with the unit and it is being replaced. My dealer also had a buzzing problem when he hooked it up.

Bundy, I hope the problem is just with the unit itself. Ground loops are a pain, but using a ground isolation transformer (MAGIC) on the incoming cable TV line eliminated all my ground problems and I do not need cheater plugs. Good Luck.

I had a wicked ground loop hum with my current BK ref 30, my previous gtp 830 and ACT3. All were corrected using a cheater plug at first and now my Monster hts5100. My culprit was the DSS cable. This was a nightmare to find as I spent hundreds on cables etc and then tamed the problem with a cheater plug (groundless adapter) on my Parasound amp. Then I corrected it by recrimping the dss coax cable without the outer ground sheathing and then fixed it properly with the Monster. Good luck. Definately check the coax cables as they are the most likely the problem.

Floating grounds are a bad idea. Don't do it (assuming you mean disconnecting the chassis ground) since it could potentially be hazardous. Always keep chassis to earth ground (via power cord). Good advice above. Good luck!