Too many ovens, deep fat fryers and electric showers.

[isuckedmandelsonslemons]

OK. it's now 7.04 and there's been a marked improvement. Not that I'm getting obsessive about it.

[trio leo]

SIMPLY PUT!!!!!
some of us don't know an Ohm from a Watt!
enjoy your music
Al

Simply put balanced mains use a transformer with its centre tap to earth thus giving 240V input and a 120V +ve and a 120V -ve output. When these are summed the equipment 'sees' 240V
Common mode rejection = all (most) of the crud gets dumped to earth.

It's not re-generation, but can work very well.
Note - you cannot wire these directly to a house main, equipment must be fed directly from them.
They are great at stopping transformers from buzzing, but they then buzz instead. I keep mine on the opposite side of a wall outside the listening room :-)

If you want to have a look at some then AIRLINK transformers sell them.

Virtually all recording studios (and the BBC) use balanced mains to help reduce mains noise.

[isuckedmandelsonslemons]

I'm happy to confess that I don't know an Ohm from a watt. At least when it comes to electricity. I fully understand watts when it's related to cycling or rowing but I don't suppose that will do much good.