Do you think the difference in your M80's is just a mid-bass "hump" caused by the boundary effect of the wall? Have you tried to EQ it? Since your setup is temporary, I'm guessing not, which leaves me with more hope, at least temporarily! From what I've been able to find on AVS about my situation (which isn't much) the spacing behind the speaker seems to be more important. If the first reflection point is acoustically treated, then it may not be too bad. And whether my left speaker is 1" or 5" or 8" from the wall, won't I have some EQ issues no matter what? Is 1" that much worse than 8" in that regard?
As for building a screen frame and putting M60's behind it... that setup would stick the screen out over two feet into the room!
