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.

No offense but that explanation Re two waves interfering etc. Is either incorrect or incomplete since you can under good circumstances get a reasonably good soundstage with a mono recording and a single speaker, for which there is obviously only a single wave. I'm not saying there isn't interference between the left and right channels in stereo I just don't believe that explains how we get to the point of a great soundstage. I suspect there are many reasons for great soundstage, including but not limited to, noise and distortion produced by jitter or mechanical vibration, magnetic field interference, scattered laser light in digital, seismic vibration, interconnects and fuses in the wrong direction.