Huh, interesting. Completely unscientific, but just monkeying with my phase invert switch (which I have otherwise ignored) to more result than I suspected. Normal phase, my soundstage is generally centered 4-5 feet behind and 2-3 feet above the speakers (to the extent of "centered" bits, such as a centered vocal track), with lateral extension out to a couple of feet beyond the speakers (left/right), and identifiable depth separation range running about 4-5 feet(ish) (from the energy center of "centered" bits behind the speakers forward up to between the speakers, and then to a generally lesser extent, extending further back from the center track). On deeper and wider recordings, such as orchestral bits, often extends both deeper and wider, pretty much in a cone back from the listening position, although estimates gey impossibly more impressionistic and hazy very quickly. But, generally, mine lives up and back from the speakers (and listening position).
With the few tracks I just experimented with, phase inversion seemed to flatten any depth of the soundstage considerably, while at the same time moving it forward several feet, almost up to between the speakers. Speakers are generally very "laid back", but the phase inversion made them much more forward -- not a lot, mind you, but definitely more so.... Interesting.
