I'm not sure if this is comb filtering, but I ran a test once with the on-wall M22 (mounted on the wall) vs the Bookshelf M22 (mounted on the stands designed for them). I had a sound abnormality with the on-wall, but not with the bookshelf.
I played a constant frequency at a constant volume level, using a CD designed for testing and adjusting your speakers.
Then using a Radio Shack sound pressure level meter, at a distance of 10 feet from the speakers (and pointed toward the wall with the speakers, without any rotation of the meter), I slowly walked from one side of the room to the other side, while watching the meter.
With the on-walls, the digital display would show different volume levels every inch or so, sometimes, by quite a lot.
With the bookshelf speakers, the volume was at a constant level as I walked.
Not sure what that proves. But, by just listening at normal source material, I couldn't notice anything that was off.
I'm attributing this abnormality to having speakers mounted on the wall, and not to any defect in Axiom speakers. Similar speakers from other manufacturers should show the same thing.
