Ed, welcome. That's technically possible, of course, but having the main channel sound coming downward from that height would seem to be less natural(never tried anything like it). I'm aware of at least one member(samandnoah)who wall-mounted his M22s, but nearer the ceiling than the floor and tilted downwards. Especially if the speakers were mounted upside-down, with the tweeters nearer the listeners, this might be a little better than the ceiling.

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Enjoy the music, not the equipment.