The illusion of soundstage.

The ambient information of the recording venue including reverberant decay, echo, first reflection and other subtle queues are captured in the recording thus two speakers can reproduce this information. Thus, depth, width and height dimensions, the 3D sphere or cube of the location as it were, should theoretically be reproduced (on a capable system). One might have to struggle a little bit to extract all the ambient information from the recording that’s there to extract but theoretically anyway it’s there.

So what i really was looking for was how, physically, sound waves can appear to be originating from outside the width of the transducers. i can imagine with an electrostat... but in phase or not, how does the wave(?) appear to come from  a different place. i am a visual thinker and want some sort of representation in that sense. thanks for all of the replies btw

Look up head related transfer functions.  Short explanation is you never hear a flat response.  Sounds that reach your ears from different directions have comb filtering effects, which your brain interprets as direction.  If you can fake those effects through sigmal processing you can fake the direction.

erik's got it sussed, and geoff's got the clues....HRTF is why headphones work so well, and the 'ambient' (whether real or 'created') is what we experience with any given pair of speakers to a greater or lesser degree.  And then we devolve into where and how our speakers are placed in a given space, what the space consists of  (what's in it, what's not, how that's arranged, hard/soft surfaces/materials, ceiling height, width/depth, toe-in/toe-out (sounds like Arthur Murray to me, two, three, four...), what you've drunk or not, etc., ad infin...

You either go bonkers with creating the 'perfect' space, which will Still be a relative rationalization unless you're an audio engineer with a talent for spatial calcs of a mind-breaking sort and a better than modest budget OR you can 'ignore the room' (per Linkwitz) which is where I'm at (it's a leased space that I can't go nutz in, and I'm cheap) OR you can do the best you can with whatcha' got with the furniture that's there and the SAF.

In the nutshell most of us occupy, that's the devil's deal.  My omni's complicate the issue, given what they do in a given space.  So I play with active eq, a tad of delay, and strike a deal with the space which is Very 'Live' (everything is 'hard' and unforgiving...).

It works well enough.  Been in worse, been in better....

Wait, wait wait! :) HRTF is a real thing, that being said, I'm a huge believer in acoustic treatment and bass traps. If in doubt, call GIK Acoustics for a consultation.  

Not only do their panels work wonders on imaging and smooth great sound, their soffit traps have enabled my subwoofer and 2 way speakers to play to reference quality. I have so much lyrical, smooth and strong bass I can use music to treat kidney stones. :)  Soffit Traps FTW!!