Floating the Ground

My B&K Ref 30 is sick and not working quite right. I am awaiting the arrival of a new Ref 50 but they keep delaying the shipment.

One of the problems is a terrible hum in my speakers coming from the preamp. It doesn't matter if the ref 30 is on or off, if it is plugged into the power source (wall or conditioner) the hum immediately starts.

I think floating the ground on the Ref 30 would eliminate the noise but I don't know for sure if there is a downside to doing this until the new Ref 50 comes in.

Any power experts out there?
Do you have a cable tv line? If so there is a chance this is creating the ground loop hum. You could try floating the ground, from my experiences, this helped, but didn't eliminate the hum altogether. You could try one of those cable ground isolaters (like the Mondial Magic Box) also, if you have a cable line. I found more success with the Magic Box than with floating the grounds.

Good luck,
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.
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.
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!
floating grounds is a great diagnostic tool even if not done permanently it can help to point you toward the problem or is useful in the process of elimination
If your stereo is hooked to your cable TV I had the same problem. Here is a cheap fix. Go to Radio Shack get 15-1140 and 15-1253 300 ohm to 75 ohm matching transformers. Connect the 300 ohm sides together. Install the transformers at the TV cable line. This should solve your hum problem and cost you $7.00.