E—Thanks for such comprehensive clarity; I generally concur. But my simple comment (that it's easier to phase-match subwoofers-to-main speakers when all speakers are sealed, not ported) was never intended to apply to idealized environs filled with bass traps and EQ correction. Nor did I intend that phase matching be conflated with time-of-arrival correction. It's generally not possible to accomplish the latter in the average home living room because decor dictates that the subs go into the room corners and the mains go up front, more centered. Given these typical limitations, it will always be easier to synchronize the phasing (at the xover frequency, at the prime listening location) if the speakers are sealed—not ported.
The extent of the phase convergence will be determined by the prevailing acoustics. In my own living room (no bass traps, strict WAF control), measurements indicate that closely matched phase won't prevail beyond a few feet from the prime listening location. Regardless, accurately phase-matching the subs/mains yielded significant audible improvement, and an instrumented means to accomplish the match was lots less tedious than doing tweak-and-listen trials.
The extent of the phase convergence will be determined by the prevailing acoustics. In my own living room (no bass traps, strict WAF control), measurements indicate that closely matched phase won't prevail beyond a few feet from the prime listening location. Regardless, accurately phase-matching the subs/mains yielded significant audible improvement, and an instrumented means to accomplish the match was lots less tedious than doing tweak-and-listen trials.