i have yamaha htr-5990 it is able to be switched between 6 n 8 ohms. i running 7.1 at 8 ohms my 1 speaker blew so i ordered yamaha ns-333 bookshelf set at 6 ohms will it be best to leave reciver at 8 ohms to run 5.1 sonys at 8 ohm and yamahas at 6 ohm or should i switch reciver to 6 ohms