You are not going to get much for surround effect with the side surrounds mounted that far behind in diagram #2. I would keep the side surrounds in the same position as in dia. 1. The rear surrounds are ok way back there and yes, M2 or M22 would be the speaker of choice. They would throw the sound more forward to the listening positions. Not sure if they would be much benefit with the couches behind that wall though. The wall would effectively block the sound from reaching you.


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