I see. I had 7.1 with 4 QS8v2. I could never hear the rears. I tried other speakers back there also including M100. No difference. Maybe it's my room. Then I got two QS10s and 5.1 was all I needed.

If the QS8 sound good behind you, the QS10 will sound even better. My QS8v2 were puny compared to the QS10.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated