I have 3.7i (and one DWM) in a room that is small and large. :-)
It is W:8.5 L:21 H:7.1
The speakers are all placed approx. 4.2' from the wall behind.
Main-speakers approx. 6" from the side-walls, tweeters inside and therefore quite toed-in.
The DWM (low-passed at approx. 100Hz with series-coils, very damped higher frequencies i.e.) is placed directly at the inside of the left-speaker.
The books at the sides are arranged in tapered/angled rows for re-direction of the first side-wall-reflexions.
I have no comparisons to other rooms or other (but very minor differing) placements in this room, but the percieved stage-width, soundstage-depth, bass-quality (clean-ness as well as substance and depth) is very satisfying. I think that the fact that the high resolution makes it sound that there is much space beyond the speakers - and NOTHING AT ALL seems to sound as it is in front of the line between speakers - makes the percieved width of the stage much larger than the seemingly narrow arrangement may suggest.
The arrangement is nearly as on this photo. But the DWM is now placed directly at the left speaker (and some other minor changes done since the photo was taken).
