So after tinkering around with my modded marshall I've found that while it produces some noise. A large portion of it disappears when I touch the bridge of my guitar (consistant effect when trying a number of different guitars).
Some history..... my friend and I were never able to isolate a slight buzz in my hometheater system as well as the 2.0 stereo in my bedroom. In both cases they are slight but if you know to listen for it, it is there.
So I suspect there might be something with my house's electrical system.
What are my options? Is there a cheap fix for at least the guitar? As that's the one where it is most dramatic.
How old is your house?
Main grounds are usually run from the electrical panel to the main water line, right where it enters the foundation of your house.
It's possible that over time, some corrosion has built up between the ground cable and the water line, preventing a solid connection. I'm not sure what the best fix would be, but that's a good starting point to investigate.
I can't imagine it would cost too much to have an electrician run a new ground, but that may depend on how far it has to go, and whether your basement is finished.