I have perceived varying levels of soundstage depth in recordings themselves and in the way the music is presented via my equipment.
Much improved speakers revealed this.
My response was something like, “wow, the distance between those cymbals and the lead vocal seems physically pronounced.”
I find soundstage depth to be an interesting aural perception.
Mono recordings from the ‘30s and ‘40s are recordings where I do not “see” a tall, wide, expansive, immaculately separated combination of elements, but a narrow, short, yet wonderfully deep “tunnel” where I can “see” into a deep background.
Just my personal experience.
I find many modern recordings are very “shallow.” Right up front and dry, almost like a pencil sketch on paper instead of a deep, 3-D experience.
Something antithetical to such a presentation might be, say, Rudy Van Gelder recordings from the ‘50s or ‘60s, or September of My Years by Frank Sinatra. A far more palpable sense of physical space between the various individual sonic elements and a far more dynamic and expansive overall presentation in terms of depth, width, and height,