Rear wall effect on sound stage location?

"Center stage" will ( or at least "should" ) vary with each recording. While a lot of what you hear is based on room acoustics and the gear that you are using, spacial cues are derived from the source material and the way that it is mixed in terms of frequency response. For instance, a female vocalist that is recorded "loud" with a lot of upper midrange will sound closer or more "forward" in the soundstage. The same singer recorded a little quieter with less high frequency content to her voice will typically sound more distant or further back in the soundstage. Obviously, frequency responses of a speaker / room can alter this quite a bit with "peaks" and "valleys" playing havoc. This also has to do with delay and arrival times, so it is VERY complicated to say the least. I wish i had a set answer to give you, but you've stumbled onto one of the things that explains why some systems sound so different than others. Sean
>

In my room, 14' x 20', when I had the speakers on the long wall, the soundstage is even with the speakers. With the speakers on the short wall, the soundstage varies depending on how close the speakers are to the back wall. In general, I think that the further away they are from the back wall, the more depth there is in the soundstage. Your theory seems to be true based on my experiences. Of course, you don't want the speakers too close to the back wall and you can get a general idea of where they should be by going to

http://www.cardas.com/insights/index.html

and clicking on "Room Setup." (In your room, Cardas would recommend that your speakers be about 8 feet from the rear wall.)

P.S. Rear Wall = wall behind the speakers

Do you have anything to prevent reflections off of either wall. Some of the difference might be tamed by good room tunes.
Without having seen your arrangement it is impossible to answer accurately but the reflections off of the walls can cancel signals and alter your soundstage not to mention your frequency responce in that room.

Don't overlook your individual cabling, components, and speakers and the synergy thereof.

If your speakers are properly positioned and the room acoustics are adequate, yet your friends all have a slightly more 'forward' presentation for say female vocals and you do not, there is a possibility that one of your components is slightly recessing that part of the spectrum.

However, I'd recommend starting out by bringing your speakers about one foot further out into the room and see what that does. I believe the front center of my woofer is about 5.5ft from the back wall.

-IMO