M50 + VP100 sounds like a great combination. You probably wouldn't want smaller speakers 'cause nobody listens to good rock with the volume down

Remember that surrounds are supposed to be on the side walls, not behind... don't suppose that helps ?

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8