Strange Klipsch thing

What I'm suggesting is that the early reflections from nearby walls might mix with the direct sound, and the combined sound might be perceived in such a way as to distort the original recordings sound stage.
And, oh yeah maybe the other thing too. ;-)

The thing is, I do not see how there can be any depth of soundstage without reflected sound. Our choices in general regarding how we locate speakers away from rear walls in order to get depth of soundstage would seem to support this. Every system I have ever heard with good depth of soundstage features speaker placement away from rear walls in particular. The extreme case I have seen that set the benchmark were the omni mbls with lots of space behind and to side walls as well.

In lieu of an anechoic chamber to experiment with, imagine placing your speakers outdoors with no wall behind them. Would you get any perception of depth? I do not think so. Try it and see!

Width of soundstage is a different thing. That you would get in the outdoor listening space. Early reflections were side walls only added could only be detrimental only in that scenario I would envision.

The balancing act comes in that distance from the rear wall also tends to reduce bass coupling and levels at the same time as potential imaging depth increases. So speakers that strive to do depth of soundstage and bass well together have to take that into account.

There is (sometimes) reflected sound on the recording, from the venue in which it was recorded. This depends a lot on the recording techniques and the venue. IME, the venue's contribution is more often found on classical recordings and less often found on pop recordings.
That's not to say it can't be supplemented by the reflected sound in the listening room. The distance/timing of the reflected sound in the listening room can supplement or detract from the recorded soundstage.

Yes.

For it to work well, the subtle 3 dimensional sound cues are captured in the recording to various degrees (or not).

Then the playback system reproduces them in the 3-D space of your listening room, to the extent that the playback system is accurate and detailed enough to reproduce them. Distance between transducers and the rear wall and adequate proportional levels of first reflection sound off the rear wall is needed generally to accomplish this.

Omnis like mbl do this to the nth degree when set up properly in a large enough room with lots of space behind them and from side walls to minimize early reflections there.

Highly directional, front firing speakers that also rely on coupling to walls or corners for bass like Klipshorn are at the other end of the spectrum.

"Dan_ed; Reflected sound. So what you guys are saying is that depth is a coloration.

I think I am to some extent. Maybe the better word is presentation rather than coloration. To be honest about it, any rear firing driver is there to create (not re-create) a sense of added space. I like this effect but I know it's a derived sound.