ground loop HUM please help

The best formula for avoiding ground loop hum is to only ground one component, for example maybe the preamp. Use cheater plugs on the rest of the components, they are still grounded via the interconnects because they are connected to the preamp that is properly grounded.

Granite Audio makes a device called the Ground Zero that should solve the problem. It's a bit pricey but comes with a 30 day trial.

Do you have cable tv/music as one of your inputs? If so try disconnecting the cable input and see what happens.

The cheater plug will work just fine with no damage to your amp.

I have a Krell MCX 750 driving my Wilson XS sub. A ground loop hum resulted which drove me crazy. I spoke to Patrick Bresnahan at Krell. His advice.....get a cheater plug.

Sounds like the problem is ground related. I had the same problem with my Krell KSA 250.

Some suggestions
1. If your Preamp is a 2 prong plug style, plug the Preamp and the Amp into different circuits.

2. If the Preamp is a 3 prong use the cheater on the Preamp only leave the Amp with its 3 Prong in tact. Still try different circuits for each.

3.If your Amp has balanced and RCA input and you are using the RCA make sure that the copper jumpers have been inserted into the Balanced inputs.

4.Most hum comes from Video sources try unplugging any RF or Video inputs to your Preamp to see if the hum disapears.