Darren Heal:
However, I'm currently in exile in the Northeast of Scotland where the electricity is virtually all hydro-electric, and therefore supremely smooth to begin with
Erm????
The way the electricty is generated makes absolutely no difference, as the generators which produce the electricty are effectively the same. The prime movers (the bit that turns the generator is different)
Nuclear, heats water, makes steam, steam turn turbine, turbine linked to generator rotor
Hydro-electric, Potential energy of water in high resevoir is converted to kinetic energy as released down sluice chutes which turns turbines, turbine linked to generator rotor
Diesel Whether runnuning on Gas or Diesel, linked directly to generator rotor
Coal, heats water, makes steam etc etc
Gas turbine linked directly to generator rotor
I agree with you reference the interference on the residential mains from microproccessors etc but only within the home concerned, it is this you are filtering out, by adding screened cables you are preventing your cables being used as giant aerials. Hence the end of the argument "what about the miles of cabling to your homes". The only switching that will affect your system is high load devices such as fridges / freezers white goods / kettles etc. If you separate your hifi onto a dedicated circuit and have RFI filters (Tacimas) with screened mains cables you can do no more. Its all about stopping interference getting in locally.
Makes no difference if you live in heavily industrial areas as they generally have their own feed, and the domestic supply is separated at local transformers.