A very illuminating study was conducted in which short-duration low frequency signals - including mere fractions of a cycle - were digitally created and played over headphones (to avoid room effects). Listeners were UNABLE to even DETECT the presence of bass energy from less than one full wavelength. Consider how long wavelengths are at low frequencies and you’ll see that, unless your room is very large, by the time you BEGIN to hear the deep lows, that energy has already reflected off of multiple room surfaces. In this context, a difference in subwoofer arrival times which amounts to a tiny fraction of a wavelength is inconsequential.Herein also explains why high damping factors are overrated! The ear cannot detect instantaneous starts and stops if less than one waveform; it is the ability to stop a woofer that is trotted out in the discussions about damping, which goes something like 'Imagine a pulse which starts and stops...' and of course you can't hear that, and further doesn't exist in the real world.
Not meant to derail the topic!