I think there's a fine line to find the sweet spot for optimal bass, in regards to how close to the wall it should be. Too close is going to muffle it, too far is going to lose the wall's reinforcement.
I know you don't have a lot of room on those shelves, but I'd play around with the spacing and see which gives you the best result.
What sub do you have? Properly calibrated it shouldn't sound like you have a sub at all. It should simply sound like your little M22's are full range speakers. Boomy bass
is really annoying. If you have a sound level meter, be sure to set your sub properly. If not, it'll keep getting mysteriously switched off.
