The situation my acquaintance was describing is in fact similar to what my situation will be... but is not now. His logic made sense, though there was no science to back it up. He just wanted his roll-offs to match. *shrugs. Lets call it personal preference. I tried very hard to not make a 'factual' claim about it, hence why I called in the Big Guns to help clarify, and for me to learn some more!
For me, I'm using the X-13's extended (15hz) and the rolloff is all in infrasonic territory. As best I can tell having played with some test tones, my hearing stops at ~23Hz. I can't hear that rolloff, so for me, I'll be OK. Plus, my ears aren't on the top of their game. 'Gonna take a minute or three to get them trained back up!
Now what Snake just brought up is a topic I'm really interested in exploring from a theoretical standpoint. If
audible... would rolloffs of differing qualities within, say, 10Hz be heard/noticeable? What might a person hear as a sign something is wrong? Or would it not even be a thing?
And this!!! I want to learn more about. The logic behind Bass Managemment as I understand it seems to be largely a bandaid for science and the masses interacting. I would love to find a way to defeat the bass management and run my Phil-3s full range while still using my subs to augment LFE for everything else below 80Hz, and fully employ the extension from 25Hz down to 15Hz.
Maybe I'm being silly, and I can accept that if it makes sense.
But This is a question that has been tumbling around the inside the old brain for a few weeks now!