Is there a recommended minimum clearance dimension from the back of the speaker to the wall? Mine are on a 24" deep shelf, so there is some latitude for moving them from to back.
Thanks!

Welcome!

I would be more concerned about the distance from the front of the shelf--boundary effects are not your friend. If you can put the speakers right at the front edge of the shelf, they'll sound better.

Like Ken said, move the speakers to the front of the shelf so the front edge is flush or better yet protrudes slightly over the shelf edge to eliminate boundary effects. The M22's are 8" deep which would leave you with 16" behind the speakers with your shelf depth. That is tons of clearance in the back.

Enjoy.

Thanks for your reply. I don't want to move it all the way to the front...too tempting for little fingers. Would it help to raise it up off the shelf a bit? How much would make a difference? I could probably go 6" max.

Joe, welcome. Ditto the previous replies. The sound bouncing off the shelf below affects clarity. Raising it a little while still keeping it recessed on the shelf doesn't help. Keep it that way only as a last resort.