Ok, so I made a little test here.
A second of stereo silence, with 10 cycles of 1000Hz in the middle of it, with the right channel delayed by 1 ms, endless repeat playback.
It sounded sort of like a click, located only in the left channel when listening from the sweet spot.
Hmm. Increased the length of the tone to 100 and then 300 ms to see if it would move back to center once the initial transient had passed. Didn't seem to.
Hmm. Maybe the "click" of the tone starting abruptly overwhelmed my hearing the tone or something like that, so made each track fade in over 3 cycles and fade out over three cycles.
Still locates to me as being in the left channel and remains there with 1 cycle delay on the right channel despite having 298 cycles that are in phase.
Hmm... Sleepy, so will have to pick this up again later.
Early simple-minded conclusion: The relative timing (phase) of the "attack" audibly locates the tone left/right of center in the soundstage, even though the body of the tone is identical in both channels, i.e., in-phase and equal amplitude sine. Not sure if the timing of the release contributes spatially yet - untested.
300ms 1kHz test tone, one cycle delay in right channel, 3 cycle fade-in and fade-out:
View attachment 4211