This worked in my mid-size listening room, which has carpet over concrete & drywall (over 2x6 frame with blown-in cellulose) walls and ceilings (14.5' x 17' x 10')
1) Remove about a lima bean size piece of putty from each PR
2) Set mid & tweeter controls at 11:00 (ignore factory suggestion!)
3) For best imaging, distance between speakers (tweeter to tweeter) should be 3/4 the distance between your head and each speaker. For so I positioned the speakers 100" apart.
4) Toe in so the tweeters are on axis with your head.
5) Measure distances between speakers and adjacent walls, move until they are perfectly symmetric in the room (within 1/8")
6) My speakers are 17-22" from the front wall (measured from each rear corner because of toe in) and max 35" from each side wall.
I found this to work very well. Last step for me is improving room acoustics -- I have eight 2' x 6' Respond Panels and four 6' Geometrix bass traps on the way from Acoustics First. I'm hoping by killing reflections from the front and side walls I'll get even cleaner sound and more precise imaging, and the bass traps should help reduce in-room cancellation which should smooth out and strengthen low frequencies.