OK, Frank and Stehno, it took a while to get here, but I now realize that we are describing the same thing in slightly different ways. I have heard the type of sound/system you are describing. And I have written about them in posts. This thread is the first time that Frank's approach has been described in a way that I can understand, in the sense that it is the sound of the system or experience, and beyond his previous ( I think, incomplete) explanations of modifying electronics.
What you two are describing, I have experienced and described as a sense of Presence. That is, it is a sound so convincing that I almost believe that I have been moved to the performance space in the presence of the musicians. These systems are rare, and I have heard them.
I agree that when everything is good, one does not need multiple channels to sound convincing. Two channels, done very well, are certainly enough. And the systems can be fairly modest by high end standards. I also agree about Stehno's comment about the wall of sound. I have heard this in systems, and it is artificial, unless one is talking about recreating an amplified live rock concert. This can often sound like a wall of sound. A symphony or jazz quartet, never sounds like this.
Stehno, I do not mean that sound is coming at the listener from all directions. It is coming from the image of the musicians in the recording at the front of the room. BUT, it then washes over the listener, and his experience is immersive like at a symphony. There are reflected sounds bouncing all over the place, and direct sound coming from the stage or front of the listening room. I still don't think of it in terms of a shape though.
Another key element is the disappearance of the system. When all is sorted out, the system is no longer a part of the experience. Only the sound.
One more way that I recognize that a system is capable of doing this is when I hear the distinction between the source of the sound, i.e. the musician, in space and the sound that the instrument makes. They are distinct from each other. The musician with his instrument is fixed in a place on stage, and his image and scale should remain as such. However, the sound emerging or exploding from that instrument, rushes out toward the listener, and is expanding in scale and position. Systems in my experience that can make clear this difference, are capable of sounding convincing and believable.
Al M. has also written about this phenomenon with certain systems and particular recordings.
I just did the experiment that Frank suggested up thread about moving in a straight line from the sweet spot up to the plane of the speakers and then off to one side, getting closer to one speaker. In my system, the location of the instruments remained the same, though standing up made the stage seem slightly lower. It then remained slightly lower as I walked around the room. However, the locations of the instruments remained fixed, and the sound seemed about as natural everywhere in the room. Tone, dynamics and resolution remained very similar, however, once I returned and sat in the sweet spot, my perspective to the stage seemed more like my actual seat in the concert hall about twelve rows back in the center of the orchestra. The scale and imaging were more realistic when seated in the sweet spot and the presentation was more convincing, but I would be hard pressed to describe the sound of individual instruments as being less realistic in terms of timbre or tone. Volume of individual instruments changed as I moved about and approached the speakers, but their relative positioning on the stage seemed to remain. I dare say, it was a bit like walking around on a stage among the musicians. Of course, ultimate scale was smaller, sound pressure less, and clarity not quite the same as the real thing, but it was convincing, nevertheless.
I only tried this listening to one LP: Heifetz/Piatigorsky playing Brahm's Concerto for violin and cello. I may try it again with a variety of recordings, but I think I finally understand what Frank is getting at.
