To Analog Scott:
I, too, am skeptical about reports like this. But that doesn't necessarily mean sbnx is not 100% correct on both the sonic importance of tiny speaker position movements and on his ability to hear differences due to tiny speaker position movements.
If you and I are skeptical it means we have to face the very real possibility that our hearing simply isn't as good as is sbnx's hearing on these particular sonic dimensions.* Our hearing simply may not be good enough to discern the particular differences due to tiny speaker position changes sbnx is reporting.
* Obviously, different people are different, and different people have different hearing sensitivities and different hearing strengths and weaknesses. I think I'm better than average at being able to discern channel imbalance and overall tonal balance and a sense of transparency on vocals. I think I am worse than average at being able to discern ambient soundstaging cues and proper integration of drivers.
I am not going to make any claims of superior hearing acuity but my skepticism comes from a modest understanding of speaker/room acoustics.
1/16 of an inch represents a wave length that is a couple orders of magnitude above the Shroeder crossover frequency range of any real world room. For there to be any room mode issues that are affected by a shift of 1/16th of an inch the space would have to be only a few cubic inches. Literally.
So there is a universal reality that anything happening with a shift of 1/16th of an inch will be strictly related to rules of vector waves. Which means any sensitivity to a shift of 1/16th of an inch of the speakers would pretty much mean the same sensitivity for head head location. The directionality and dispersion of the speakers would have to be barely wider than a human head.
The assertion that such a small shift in speaker position can be heard down the stairs from any particular position in the down stairs room is not really a matter of yours or my hearing acuity.
It’s comparable to splashing around on the beach in Malibu and someone claiming they can see those ripples in the water on the shores of Hawaii. Any of the shores of Hawaii.
That wouldn’t be a matter of someone having sharp enough vision.
So yes, I am skeptical. But I wasn’t going to push it.