If you have a ground loop problem, which usually shows up as a anoying buzz in your subwoofer in the 50-60Hz range, then you'll just need a ground loop isolator. I've tried different ones for $20-100 and they all work about the same. The $100 that I currently am using is nice because it has an inline fuse to protect your equipment hooked into coax from line spikes. You can also make your own (since this is a DIY forum afterall). I've read complex plans, and there are sure plenty of plans out there, but basically you need to physically break the loop by using a 1:1 coil in-line with your cable feed.
If you simply have "dirty" AC, then you should get a line conditioner. We have a rack mounted one in our studio that cost us about $200 and includes 6 AC outlets that are individually switched. It's a no-name brand, but it gets the job done. Sorry - no DIY knowledge on this one!
Email me at
astaples@diylabs.org if you need more info. I swear that bad AC is what led to my hair turning gray at such an early age, so I feel your pain!
