Loud Hum

Turn off all equipment & unplug everything. (This also gives you a chance to clean/check all connections) Start over but just connect the spkrs to the 7BST's. If there's a hum, there's your problem. If not, go through the hook-up sequence one piece at a time until you locate. Make sure to turn off all gear everytime you connect/disconnect.

It's been my experience if it's not the component itself the AC is the culprit and most of the time it's the AC & not the component. If it turns out to be the AC, do a search through the archives for ways to address this. Good luck.

If anything is on the same circuit as the dimmers, it'll introduce noise & it might even backfeed into your dedicated lines if everything shares a common ground at the panel. The only true dedicated lines are completely isolated, including the ground.

When I ran sound on the club circuit, I learned early on to avoid dimmers/fluorescents like the plague, as dirty AC was the biggest detriment to good sound. Same thing holds true in your house. I also recently had an electrician check out my circuit, as I could hear a buzzing through the spkrs. that I hadn't noticed before. He tightened up the ground in the panel, as my dedicated lines share the ground with the rest of the box. Just that little bit helped eliminate the buzz & I can only hear the slightest hiss now if I put my ear right up next to the driver. If you aren't sure what to do re: tightening the ground or anything for that matter at the panel, do not attempt to, as this electrician, who also happens to be an audiophile, told me more people are electrocuted in their own homes trying to do repairs than anywhere else.