I recently had a room built for audio only (18 months ago? how time flies). My audio conscience electician wired a 20 amp dedicated line (less than 20 feet from the box) to a single outlet. I have a conditioner/distribution unit with all electronics hooked into it. My lights and electrostatic speakers are on a separate new line.
Happily, my house is the second one from the local transformer and I live in a residential neighbourhood far from any Industrial or Retail complex. Very little to zero line noise.
I am happy....