hum, please, please help

I have a hum issue that I am starting to troubleshoot but need some help on what I can eliminate as the problem. If I plug all components in normally to the dedicated 20 amp lines I get a hum. If I use cheater plugs I still get a hum but it is quieter and somewhat tolerable but audible. If I crank up the preamp the hum gets a little louder. I know that dimmers can cause this problem. I have no dimmers in my dedicated music room but in the next room I have a dimmer switch for recessed lighting. So I decided to turn it on and turn up and down the brightness of the lights and this definately affected the hum. If I turned it way up it got a little louder and got more quiet as I lowered it and when I turned it off the hum stayed like it was before. So my question is if this dimmer is affecting the hum or contributing to the hum is this a ground loop issue or a grounding issue or an electrical issue? My equipment consists of Escalante Fremonts clayton audio m-300 monoblocks, hovland hp-200 preamp and amr cd77 for cd player. I also tried running a ground wire from my preamp to one of my amps and this did nothing. Any help would be very aprreciated.
You might try the following (if you haven't already - you did mention cheater plugs). Create a makeshift star ground configuration by using cheaters on all your components except the preamp.

Sounds like a probable ground loop problem to me, and a star ground often helps. One other thing you might try is listening to your system while turning off the other circuit breakers in your panel box one at a time. If you can isolate a circuit that is causing the problem, you can try replacing or moving the appliances drawing off that particular leg.

If all that fails, you can try an AC isolation transformer. The good ones are expensive, but even without a ground loop problem they definitely enhance the sound of SS gear. I'm really impressed with my Furman transformer. I believe music direct also sells a star grounding separate-chassis unit via their website as well that might be worth a try.

Hope this helps.

Good luck and good listenting.

As an addendum to the excellent advice Mark gave you; an alternative would be to have an electrician install a dedicated circuit(s) with an isolated/dedicated ground. This would certainly be a minor expense compared to the cost of your system. I didn't know what star grounding was, but found a good post on that subject as it applies to an amplifier. It also gives some insight into the hum problem with audio gear and household circuitry. Thanks for that, Mark.

This might be too simple, but how about replacing the dimmer switch with a regular switch? Dimmer switches are notorious for noise. Otherwise I agree with Mark and Marco that an isolation transformer should resolve the problem, but cost a lot more.

Great article, Marco, thanks.
Some good advice from others. A few other things to think of and check. So your saying that you are lifting the grounds all all your pieces of equipment and you still get a hum ? Are they all plugged into the same outlet ? I do suggest lifting grounds. If your wanting to ground your equipment for fear of electrical shock from a electrical storm I have found the preamp to be the best piece to ground. With the preamp grounded all components share the ground plain. If you do put in dedicated circuits make sure that if you put more than one that they are on the same side of your electrical panel. You have 220 coming in to your home and then it is split at the panel and each side of the panel is out of phase with the other that can cause and will cause a hum. Also how are your circuits grounded if your using a ground ? you might play along with the grounding circuit of that line. Some like using a copper buss bar pounded into the ground. I have also had good results grounding to water pipes in the home. Try lifting all grounds first, then just the preamp and all plugged into one outlet. I have also had issues were other house appliances were running like refrigerators etc. If you have tubes it could be a bad tube as well. There are a few things to try and if that doesnt work feel free to email me at Kevin