Is there a problem with using together M22/VP150,QS4 and M80 in a 7.1 set up? They are all 8 Ohm speakers except for the M80 which is 4 Ohm? What setting do I set the receiver to 4 Ohm or 6 Ohm? I have the Onkyo 805. I have all except the M80 (was debating between the M60 vs M80)?