Hum issue - driving me more crazy

Has the system always hummed or did it start when something was changed?

Hello Imdoc, Hope my obsessively detailed response was helpful in your quest to rid the hum. I am a firm believer now-a-days in running things balanced. Took years of trial and error, and a whole hell of alot of gear, cable, and subwoofer swapping. But balanced is the thing for me.

A suggestion for you regarding balanced cables. Before you go out and start dumping your hard earned cash on stuff, try some "professional" grade stuff. For whatever it's worth, I don't have any idea how $90 balanced mic cable from Guitar Center can be referred to as "professional", but I tried some of their "house" brand balanced cables, and also some MOGAMI brand. Didn't set me back much at all, and worked just fine for a long time, (until eventually upgrading to shit that cost 40 times as much for the same length.) Try it out. If it doesn't work out, or degrades your sound at all, you won't feel suicidal for for emptying your bank account. That cheap stuff ain't all that bad sometimes.

As for lights on dimmers- Elizabeth is oh so right. Not all dimmers are created equal, with some of them really causing more problems than they're worth. I have 800 watts of halogen lights on tracks, illuminating various pieces of artwork in my listening room. I too had hum because of them- once. Not anymore. Lutron, and Leviton make something called a (I KNOW I will screw up the spelling on this, but...) Colloidial coil?? something like that? It's essentially a "anti-buzzing" coil that is wired into your electrical supply line, between the dimmer and the fixture, lamp, etc. Works like a champ and completely kills the buzz caused by dimmers, and halogen bulbs. Lamps Plus sells them, or at least they used to. Try your local electricians supply house.

Unplug any cables (RCA, F connector, etc.) from your Cable TV/Sat/Antenna and see if the humm disapears.

Rwwear - hum started at time of new XOVER. BUT this was also same time that I "buried" the IC's under the floor and got new IC's. Thus multiple simultaneous changes. IC's above floor are great.

Ozzy - No TV or SAT in system - LP, DAC and CD player are only sources

BALANCED cables has fixed all issues even allowing me to use the dimmers in the room without a peep. Even slight hum in Vinyl subsystem (2 chassis phono preamp) is gone.

I don't know enough electronics to understand what "I fixed" (or more likely unbroke) but the end results are outstanding for about $120.00 worth of cable and connectors. All I can say is in my application/room/system -> Balanced IC's are great.

Thanks to all. Have a memorable Memorial weekend

Yeah, if going balanced fixes it, go for it. It could take a long time to figure out what is happening. Enjoying music is much more fun. ;-)