Hiya,
I'm moving my living room around and have to rearrange my audio set-up as well and i have a little problem.

My room is 14x20 and the front soundstage is perfect. The problem is that i'm going to mount my QS4's on the wall now and there is an opening on 1 side that makes it impossible to place the speaker at a 90 degrees to my listening position.

the closest i can get it is about 40 degrees behind me. Will that be ok with the flush mounts that came with the speakers or should i buy the full metal brackets so i can angle the speakers a little towards myself and hopefully negate some of the angle?

Thanks in advance

Typically, you want around 100 (more than 90, less than 110) degrees for the side surrounds. How accurate is your 40 degrees measurement?

I'd say i'm within 5 degrees or so. My seating position will be inline with the front of a 40 inch opening that leads to another room. If i placed the surround at the front edge of the opening then it would be a good 12 inches forward of my listening position. Place it at the back edge and it's 35-40 degrees behind.

that positions 1 of the tweeters to fire directly at the listening position and the other into the back wall.

Someone else with that issue will have to chip in.
My personal reflex would be to place them 35-40 degrees at the back before putting them in front.

I had to put mine in front of the seating position and am not happy with the surround sound. The front is better than it used to be in the new house, but surround is not as good.

My only other option was pretty much in the two back corners of the room, and I didn't think that would work well either.

Just another excuse to plan for a HT room in the basement

This depends on so many factors that the best answer I can give you is that you'll have to experiment. Use a stepladder as a temporary stand for your tests.

I have mine placed 45 degrees behind me, or 135 degrees off axis from the center of the screen and they sound perfect.

Ditto what Mojo said. Experiment with different placements if you can. I spent three months trying different placements and found that without a doubt they sounded best to me in my room at 135egrees back though I had the freedom to place them anywhere. Your room and tastes may vary.

Also from what I’ve read in these papers:

http://www.dolby.com/assets/pdf/tech_library/L.mn.0002.5.1guide.pdf

http://www.dolby.com/assets/pdf/tech_library/4_Multichannel_Music_Mixing.pdf

Dolby suggests that for producing multi-channel audio the surround speakers should be 110 degrees back plus or minus 10 degrees. This is actually 10 degrees farther back than is usually referenced on the web. Not sure why, maybe things have changed since Dolby published these and they just haven’t been updated. In the end all that matters is what sounds best to you. So again if you can experiment.

Mongo, welcome. I assume that you're speaking of a 5.1 rather than 7.1 setup. It's typically recommended that 5.1 side surrounds be a little farther back than directly to the side, so that some back effect is added in the absence of actual back surround speakers. The exact distance isn't critical, especially with very wide dispersion surrounds like the QSs, and I commonly just say a couple of feet. The slightly longer distance that you describe(do it for both surrounds, even if not necessary)should be fine and you'll enjoy excellent surround sound with your QS4s.