hum from nearby high-tension wires?

I certainly believe being in close proximity to that much of an induced electromagnetic field can cause the type of problems you are having. There have been extensive studies debating whether or not there are health problems associated with this as well (I think the verdict is still out). I don't think there is any type of power conditioning device you can use to get rid of this, since the EM field is permeating everything in the vicinity. You could certainly try these devices, but they probably won't address the issue, since this EM is radiating into your electronics directly, despite any conditioning measures. You could try extensive MU-metal shielding, building a Faraday cage, in effect, but this is expensive and there are no guarantees. When I was young, we had high-tension lines (in excess of 2kV) about two miles from my home. These were huge, scary looking metal towers which emmitted an audible hum at all times. We used to go up there at night in the summer with standard 4 foot flourescent tubes which would glow at nearly full intensity as one came close to the towers.

My advice is to move.

-Richard

Get yourself some kind of battery powered audio device...a portable radio for example. See if it hums, and what happens as you walk towards and away from the transmission lines. If it doesn't hum, you have a problem with your own system.

If you can do it, I'd suggest moving. If the overhead power line are affecting your system, imagine what they're doing to your body.

All of the information your body passes, is passed electrically. Strong electrical signals interfere with the transmission of information.

Dr R. C. Brockhaus

Hey, nothing like scaring the guy. Verdict is indeed still out on EM/RF impact on human health. As far as your hi-fi, that is a problem. You can try sheets of ERS cloth and move them around to see if there is a particularly sensitive piece of equipment. could also try humbuster. I assume you have checked to see if it is coming in through your CATV.