Rear wall effect on sound stage location?


I have a large listening room (18W x 30D) with cathedral ceilings. My speakers are Vandy 2CEs placed 8ft. apart and 4ft. from the front wall. I sit about 9ft. in front of the speakers. I get a great wide and deep sound stage with vocalists/instruments that appear to be behind the front wall and slightly above the speakers. I am very pleased, with no complaints.

However, in many of my friends listening rooms with rear walls much closer to the listening area, the vocalists appear to be more even to the speakers or even in front. Does anyone know if the location varies with the closeness of the rear wall? Do earlier reflections pull the sound stage in? Where is the most desireable location?
128x128zargon
What kind of electronics are you using? I've found amps to be the biggest factor in soundstage location. Many amps offer a first row seat, some seats on the stage, some a standing row only seat against the back wall, and others all spots in between. Other electronics also affect this, personal taste dictate what is "right" for your ears....
Thanks for all the ideas, I hadn't expected so many variables. In general, where is the most preferred location for the sound stage? Behind, even or in front?

Sean: I wanted to clarify that my speakers are on the short wall and the room is carpeted with an appolstered couch and chairs. If you clap, you get some echo. I have not treated the walls although the rear wall (behind the speakers) has windows with shutters which I keep angled down for diffusion.

Bufus: Thanks for the link. I'll check it, however, there is no way I could get the speakers that far out (there is a living room and a dining room to be considered).

Nrchy: One of the side walls has a fireplace with a marble face and I'm sure that is causing reflections. Any ideas on how to deal with that?

Stehno: I never considered the components as you suggest. I will try to squeeze another foot out for the speakers. I find if I move them an inch or so each week, my spouse is less likely to notice!

Socrates: I am currently using a ARC LS 15 with a PSE Studio IV amp (ST). I am hoping to get an ARC tube amp soon and it will be exciting to see what the differences are. What is your experience with the ARC? Forward or back?
Thanks Sean and Stehno for explaining. I heard Merlin VSM and male vocal is VERY forward compared to B&W Nautilus. There was 15 feet behind VSM and 6 feet behind Nautilus but VSM still had more forward presentation.
Must be combination of Nautilus upper mid dip and beaming while VSM has a rising midrange as described in Stereophile review.
Wow and yippie! This discussions has been very rewarding for me. I spent time yesterday adjusting my speakers based on the Golden Ratio as suggested by Cardas (thanks so much to Bufus). I only had to move the speakers about 2" closer and I got them out to 5' in front of the rear wall. Then I went through a rather time consuming proces of ensuring they were absolutely symetrically placed and vertical and had an equal toe in of 1/2". Some critical listening revealed that the focus was in front of my listening position (based on an equilateral triangle), so I took reduced the toe in to 1/4" and things came into focus at the listening position.

Now comes the best part. The location of the sound stage has moved from at or behind the rear wall to well out in the room about where the speakers are located!!! Solo vocalists are now much more PRESENT and alive. I feel like I am now in the first row!

While I always knew that speaker positioning was critical and have played with it frequently, revisiting it with the Golden Ratio has finally solved the sound stage location issue that I addressed in this thread. I can only encourage others to try this as well.