Line Noise?

[Oliver Hart]

Hey guys. I just built a new control and vocal room. In the control room I have 2 dedicated 20 amp circuits (one on each side wall) spreading to four outlets. The lighting, and a few misc. outlets, is on a seperate 15 amp.
The problem is I'm getting a buzz coming from somewhere. I'm using either new cabling or the same stuff I was using in my other room (which is about five feet from my new room!) If I turn it up and sit there for a few minutes, I can here it go up and down in volume and change in frequency.
Now I do have dimmers. I new this was a no no, but I thought that if they were on their own circiut I'm good. I'm calling the electrician tomorrow to have him replace the switch. As I dim the lights up and down I can here a little effect on the noise.
But here's the real problem. Thinking the peice of shit dimmer switch may be my bitch, I went to the main box and shut it off, still too much noise. Next I turn off everything in the house except my studio circiuts. Still too much noise.
Now when I get the electrician over here I'm obviously going to ask him if he knows what's up, But if anybody has any advice, tips or tricks to help me get up and running it would be greatly appreciated.

Thanks ahead of time.

p.s. I also read in a mag about Monster products that are made for filtering out line noise. Do these things work? It says they are made for home theatre.

Thanks again

-Oliver Idiot