Hi,

The M22ti's with your Velodyne sub will be fine for that size of room. Putting any speaker on its side will alter its tonal character, some more than others. Try it with one of your existing speakers and compare. Why not consider a pair of QS4s for the rear as well to preserve tonal consistency? Or use a singel QS4 at the center rear?

Regards,

Alan Lofft,
Axiom Resident Expert (Retired)