If you have a fair bit of distance, 4ft or more, between the listening position and the rear channels you should be able to use M2s for the rear channels, otherwise I would hold out for another pair of QS8's. The direct firing of the M2s won't be much of an issue the farther away you are as the sound has time to disperse, but if you are closer the the speakers the already diffuse sound from the QS8's will/should sound better.


Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70