Mojo is finding the 1/4 wave pattern. Guaranteed the latency is greater than 5msec. The reason I know this is he is quoting a frequency. But he is spot on anyway.
The sine wave vs spl test will get you perfectly time aligned but wont account for phase alignment. Strictly speaking, phase alignment requires transfer function measurements, smaart live or equivalent. I dont know if REW does it. I use audiotools. Phase alignment is both onset of transient and cycle alignment. Uber aligned.
Dont despair! Getting a max spl at the low pass setting is dang great! I messed with some stuff today, but the full show and tell needs a little more time. I just got the 2x4 but still boxed up. Tomorrow maybe. Libations for now!
