Hello,
I didn't see your post but got your email query this a.m., and answered it. Then I saw your message board posting. Ian has already covered some of the info, but there are other issues I address, so I thought an edited version of the email to you might be of general interest.
A few inches of clearance is all you really need between the woofer and the ceiling, but it's better if you keep any speakers further away from the junction of any room boundaries (wall to ceiling, corners, etc.). You will have enough clearance if you put the bracket at the bottom of the 13-inch board. You can also mount the QS4s directly to the wall, using plastic inserts (hardware store) in a hole drilled in the plaster drywall. The instructions and bracket are supplied with the speakers. Just call Joe Vassallo, our service manager, toll-free at 1-866-294-6688 for more information on mounting if you run into problems.
Please ignore the "different tweeter" issue. The tonal signature of a speaker is mainly determined by the woofer/midrange drivers, the crossover point, and overall balancing of the drivers, not by the specific tweeter type. So don't worry about that. QS4s would be quite adequate for your room and would blend nicely with M22ti's, which I would recommend. The QS8s are better for larger rooms.
With your sub, I believe the M22ti's would present the smoothest and most neutral soundstage, as well as 3D-like imaging. The M3ti's have a rather laid-back, mellow midrange that, in my listening tests, is not as detailed as the M22ti's. I prefer the M22ti's, but many Axiom customers love the laid-back quality of the M3ti's. The M22's have wonderful power handling, even without a sub. But your sub will supply strong support below 40 Hz.
Placement a few inches out from the wall is fine, to let the port vent low frequencies. All walls and boundaries influence a speaker's sound, so you have to experiment a bit. If they sound better out from the wall a foot or so, use them that way.
Quadpolar surrounds are easier to place than direct-radiating surrounds, especially when different distances and heights are involved. They work best elevated 1 to 5 feet above ear level for seated listeners, to the sides of the listening areas, either slightly forward or to the rear. Experiment with placement before you choose a permanent location. Every room is different.
Wall mounting is always superior to shelf mounting of a speaker, unless it's an open shelf. Again, some elevation usually works better, roughly the same height as your surrounds. My multipole surrounds are at quite different heights, and produce a wonderful sense of envelopment.
Regards,
