The SMX website shows a test done at 6" and showed that the effect on freq response was very minimal at 6".

The SMX faq says 2-3" is minimum.

McCall reports using only 2" behind SMX screen, presumably with no ill effect.

Is there anything authoritative on the audible effect of having speakers 1", 2", 4", 6", >6" behind an SMX screen?

Any difference that is audible? Anything that can't be fixed by, say, Audyssey or other EQ?

I'm considering putting James inwalls about 1-2" behind an SMX screen. The SMX screen looks to me to be much more acoustically transparent than the rather substantial metal (!) grills that came with the speakers. So I can't imagine the SMX screen an inch or two in front would cause much of a problem.

I gave my Answer to this on the other thread.

From a new page on the SMX website:

The beauty of the CineWeave™ HD is that you don't need to worry about having your speakers a certain minimum distance from the screen surface like conventional micro-perforated screens. This allows you to mount your screen on the same wall the In-Walls are installed on. Best of all, you can still acoustically treat the wall behind the screen with an acoustical wall treatment.

Rueben also reported that many people have speakers 1-2" behind with no noticeable problem.