you plugged them into a television using the same RCA interconnects and a different wall outlet? if you do a Google search some owners report minor buzzing and switching to balanced XLR cleans it right up.
Honestly I think im done trying to make this work. Im experiencing way more problems than most people, so maybe its just not meant to be. I think Im just going to return everything I bought and go back to the z5500s, as sad as that is.