I have a dimmer on another circuit in another room. When that dimmer is turned halfway on, the noise from it is seen on the amplifier line. Dimmer on, noise, dimmer off no noise. (the noise is being 'seen' via a PS Audio Noise harvester blinking) So noise from nearly anywhere in our home, outside your home can travel nearly anywhere on power lines.
There are devices which can stop the high frequency noise from passing on by.
There are devices which can stop the high frequency noise from passing on by.

