Strange Klipsch thing

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.

Wow! Unsound, we seem to have found a patch of muddy, swampy, common ground. NO PUSHING! ;-)

Bravo, Russ69!

Coloration is NOT a four letter word and every system adds it to some degree or the other. Embrace the coloration your speakers and room create. This is exactly what draws each of us to the choices we make. ALL rooms and speakers contribute to colorations.

That said, I think if folks are always hearing depth from their speakers on every recording that would be a clue to me something isn't right according to MY preferences. But it could be fine for someone else.

No depth is a illusion. It doesn't exist its a trick of the senses like stereo.