IMO, you don't get THAT much bass reinforcement from wall mounting M22's that you have to worry about it. If anything you start to get better upper bass, something that I felt was always a little lacking from my M22's on stands or other placements I have tried.

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