I too have noticed this phenomenon, when I lived in my apartment. The differences were NOT subtle. All the electronics, including my alarm system and wifi were all on the same branch.
In my new home, I don't have a dedicated line perse, but nothing extraneous is shared on the electrical branch, which I think is a good thing. I haven't gone to see if unplugging the modem and wifi downstairs on a different circuit will make a difference in the house yet. But you are not alone. It was almost mandatory for serious listening in my apt.
In my new home, I don't have a dedicated line perse, but nothing extraneous is shared on the electrical branch, which I think is a good thing. I haven't gone to see if unplugging the modem and wifi downstairs on a different circuit will make a difference in the house yet. But you are not alone. It was almost mandatory for serious listening in my apt.