@millercarbon thanks for the informative and entertaining post.
Just for a bit of context, I sold a pair of full range speakers last week that didn’t really need subs. The Dunlavy 3 is a great speaker that will cover well until I reinvest in new speakers.
I’m not new to the perils of sub integration nor the DBA theory, and I’ve conversed with Duke a couple times over the years about his Swarm arrangement. I’ve setup a few successful 2+2 systems and had pretty good results with so-called difficult speakers like Magnepan and Apogee.
So with that out of the way, to benefit from the content of your post I also need some context - I’m curious to know what your mains are and whether or not you run them full range. Also, you make no reference to sub quality, only quantity. Are you saying that 4 cheapish subs can produce tight, articulate and extended bass, or is there a requisite standard or level of quality and if so, can you suggest a make/model that you see as the entry point for a successful distributed sub system.
As for the ‘phase’ affect, I only hear what I hear and see what I see. With subs inline, I hear no issues other than that stated. With subs elsewhere, there is a downside, as stated. It may or may not be phase but it sure seems like it based on the effect that I hear.
Lastly, my pair of HSU have been pretty much everywhere in the room including perched up on table tops; presently they’re against the left and right walls, tight up and with one behind the front plane of the speakers and the other closer to the listening position.
It would be cool to hear from people using subs with inbuilt room equalization to see just how successfully they integrate in a 2+2 setup.
Cheers!