Importance of wall behind listener?


In my audio setup, I essentially have no back walls to speak of. Behind the listener is an opening into a long hallway, an opening to a den (to the left of listening position), and an opening to the kitchen (to the right of listening position). I'm wondering if this is a hinderence in getting a truly 3D holographic soundstage representation. Other folks who have a near identical systems get phenominal soundstages, so I know it's not any of the equipment. The difference is they have a back wall vs. my no back wall, and their straight ceiling vs. my sloped celiling (peaked at center, dropping on both sides).

Any thoughts?
1markr

I agree with Sns on this.
You may also want to try diffusers behind the speakers. I get a very nice enveloping and palpable soundstage with these treatments!

I tried damping panels, Polyester batting, tube traps (alone), diffusion by way of artificial plants and even carpet.

In the end, RPG QRD 734 diffusers directly behind the speakers worked the best. I disguised mine with acoustically transparent cloth (good wife acceptance factor) and wound up preferring the sound over the uncovered version.
Thanks guys...

SNS, do you have any pics that you can email me? I'm interested to see what it looks like (WAF!). And thanks for the tip on the QRD 734, Albert. I will look into it.

I should also add that I have a 55" RP TV between the speakers, a foot or two behind the front plane of the speakers. I cover it up completely with 3" foam pyramid diffuser panels to reduce reflection.
1markr, you can look at my system here at Audiogon for the WAF images :^).

http://forum.audiogon.com/cgi-bin/fr.pl?vaslt&1022712214&view

Here is a photo of my QRD 734 during construction, built into the back wall.
http://cgim.audiogon.com/i/vs/i/f/1111001394.jpg

Click on room views to see the acoustical cloth wrapped around the room obscuring RPG's and damping panels.
1mrkr, I should have made it more clear that I do use diffusion behind my listening position, only on the ceiling. I use a combination of skylines and doublebusters spread from just behind 1st reflection point on ceiling to behind listening postion. Sitting diffusors on floor stands behind listening postion has not worked as well as the natural ambience of no diffusors.
On WAF, that is difficult for me to know, I have a dedicated listening room so it doesn't matter. I actually like the esthetics of a fully treated room, I'm not so sure others do.
"1markr, I should have made it more clear that I do use diffusion behind my listening position, only on the ceiling. I use a combination of skylines and doublebusters spread from just behind 1st reflection point on ceiling to behind listening postion"

Scott, I think you meant "do NOT use diffusion behind listening position"....