Kingrex, you may be referring to me. I posted my impressions of my new Pass preamp here as well. I can expand a bit on what my mentor in Vienna was talking about and how years later with the help of WBF member DDK, I am starting to realize this "natural" sound in my own system. It is one way in which I now recognize the difference between a system which sounds "natural" and one which sounds "hifi". Here is how I think of it:
Sound originates from a singer or instrument in a real space. When we listen to a recording, the system can present an image of the singer or instrument. We can localize that and we start to describe a system’s imaging and sound staging capabilities. I think of that as distinct and separate from the launch of that energy or sound out into space. We hear the hall fill with sound at a live concert. A successful audio system fills up a listening room with energy, just as a cello energizes a live hall.
I heard this energy from one singer or one cello at both the edge of the stage during rehearsals and from the director's box in the back of the great Vienna State Opera during the evening performances. Less successful audio systems simply present the image and stage and sound as something distant or remote, as if one is observing it rather than being enveloped by the sound or energy of the voice or instrument.
This portrayal of the sound generated from a voice or instrument on a stage within the imagined soundstage in our listening rooms leaving its origins and moving to fill the space we occupy, and indeed the whole listening room, is what makes the sound “natural” to me. (along with convincing timbre, dynamics, etc.) It needs to be effortless, as it is in real life.
When done really well, we leave the realm of hifi and enter the realm of the natural portrayal of sound. It helps to understand this, IMO, if we explain the distinction between the origin of the sound and how the sound then leaves and fills the space. However, in reality, it is one thing, inseparable, and a whole. One does not hear the two as separate and indistinguishable, but rather, it is one thing, and it is the incredible energy created by the bow against the strings and the wooden body vibrating.
A friend today described for me this effect in his system at home. He explained how the organ in Cantata Domino takes up a physical location in the church and its images at a location on the front wall of his listening room. But the sound is everywhere once it leaves the pipes. It breaks forward of the plane of the speakers, the front wall, everything in front of the listener and, most importantly, it fills the space in which the listener is sitting. Both at the concert hall and in the listening room. This energy becomes a physical presence in the room, not a sound and image observed in front of the listener.
This would be near impossible to demonstrate using only one system. It is better demonstrated using two different systems one that can do it and one that cannot. The system either does this or it does not. It is either natural sounding, or it is not. My system used to struggle with this. Now it does not.
This is a bit off the analog/digital topic, but it gets to the heart of why I think a properly assembled and set up audio system can sound convincing and like the natural sound of music.
Peter