hum from nearby high-tension wires?

Based on your second post, I don't think the power lines are the problem. EM fields extinguish rapidly in air - if you were between them and the ground (i.e., under the power lines) then there could be an issue but not if you are 100 feet away. My guess is you have a bad ground. I have seen entire houses with bad grounds so don't rule that out!

However, do try the fluro tube bulb test but I bet it only works directly under the power lines, if at all (too low voltage lines).

Steverw, what recommended treatments have you tried?

>>"These aren't the monster tower kind of transmission lines for long distances, they are local distribution type within city limits that have lower emissions."<<
[Steverw]
>>>>>>>>>

Just curious how high off the ground would you say the power lines are?

How long are the insulators that the wires are supported by?
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>>"There is also a large transformer station of some kind about 200 feet away."<<
[Steverw]
>>>>>>>>>>>

That sounds like a Substation. Just an example of a Substation in a residential area, 3 phase 69KV feeding the Substation 7.2KV/13.2KV 3 phase 4 wire out.

Substation near a large university could be 169KV feeding the Substation.

Best guess, how high are the power lines, and the size of the insulators?

I think the hum should be the last thing your concerned about.

Jea48: maybe 80 feet high. Insulator about the height of a large owl or hawk (maybe a foot?) (I often see them sitting on the line).