Do power conditioners help with unwanted hum/noise

Gs5556 puts his finger on the problem that has just been solved for me by an isolation transformer.

Since home heating season began this year in Montreal (and electricity use went up), I had been getting a hum on my bedroom lullaby system (HK 930, Paradigm Titan) that made it unusable for me, no matter what the volume setting. Adding a CDP made it worse, doubled the hum volume. The darn hum went up and down in volume, like a prop-driven small aircraft buzzing the neighbourhood. (OK, it was hum plus buzz... ).

I found a small (250VA), very cheap isolation transformer on eBay and it has cut the noise down to a viable level, not gone, but slightly more than just perceptible.

My main system is on a dedicated line and I get the same hum there, but at a much lower level. I've put the transport on a Deltec 500VA hospital-grade isolation transformer and the results are so good that I intend to give the entire dedicated line similar medicine.

Sean, thanks much for the tip. I have done a bit of research here and lurked eBay. The best kind appears to be what's called an ultra isolation transformer with very (high? low?) internal capacitance, on the order of 0.0005 pF. I have a 220V three-wire line (2 hot, 1 neutral, and I can run a dedicated ground) ready for use as the new audio circuit, so what I need is bucking and isolation.

I don't know if single transformers exist which can do both jobs, but that might be the ideal solution, if I could find it.

My problem is my relative ignorance in the domain. I can wire up a house and build an amp kit but I don't know enough to ask all the right questions of an eBay seller, or recognize that a tranny has the right taps by looking at it and its specs.

Could you possibly suggest a basic reference on the subject?

Thanks for the help, Sean, very much. I think I can go ahead and buy a transformer, thanks to you.