Why a "dedicated circuit" when everything gets lumped together upstream of the comnpponent? Separate line for digital? Horse schlockey. If the line goes through a fuse box with "analog" circuits, then the purpose is defeated. If the dedicated line comes into the house seperately, then it will still be pary of a general cirsuit somewhere upstream without any filtration. And there's typically enough RF in the air that using a separate circuit will still end up being a long radio antenna.
If an audio user really desires isolation, it might be better to get a hospital grade isolation transformer of sufficient capacity to handle .the equipment load Or two. Or three. Whatever tickles your fancy. Be careful to check the grounding across equipment in different transformers.