The bass is the place...

This is why I gave up on subwoofers. First, you're constantly worried about bass levels...all the time...not to mention the optimum placement.  And I never liked how my primary amp sounded with them on the same circuit.  I probably gave up too soon...but I felt like I was chasing my own tail at times.

Anyway, over the years I've developed a 6th sense in handling the room I'm in.  That has helped.  But right now I have the opposite problem: My Primaluna has a lot of bass slam...it's kinda ridiculous. This is not hyperbole. My speakers are Salk Songtowers with 5" mid-bass drivers and there is no need for a subwoofer. I can't believe how good  the bass sounds.

Anyway I hope acoustic ceilings come back in fashion. They really do make stereos sound better...no contest. 

I use dual subs placed opposite each other midway between front and rear walls. Works for me. Never tried DBA unless you count front towers with built-in so
subs plus the duals. Have to admit, it did sound sweet. 

Iy is true you need multiple bass transducers like a powered sub to get bass right across a room.

However most speakers only can get the the rest right in a single sweet spot so a single sub can serve well for that as well.

To get it all right across a large area one needs very wide dispersion or Omni speakers to start with else the solution is not complete.

When I listened to the Focal line I always said, WHERE'S THE BASS.

Swarm/DBA Duno! might be.

I use my monitor sections in a traditional way.  350 hz up planars

I use 2 Midbass units that are really the strong point of my system, WCF
12" X 2 per cabinet tuned with a 12" Passive radiator, Their tuned at 40-350hz.

I removed a lot of distortion by using and changing phase plug lengths, and profiles. Big speakers cones normally produce a lot of pressure, sound better. problem is, all that surface is a great place to collect bass at the wrong time.  38" the top of the drivers, 8 ft ceiling
In a stereo way, become very directional with phase plugs.

4  true sub units, usually only 2 at a time.  2 10", 2 12" all tuned with PR
12" tuned 20 to 40 hz,  10" are 30-60 hz , located 2ft X 3ft from the walls
None of the active drivers face each other only the passive. 3.5 cf boxed
140 lb loaded boxes.  70% decoupled from the room

8 active drivers, and 6 passive drivers, all through an Active Crossover 2494 NO DSP correction. Only crossover points. Able but not used.
350 hz down, only a passive XO  in the monitor sections, NEVER use the bass sections in the monitors.

So total of 6 units, at different heights, but a pair set up as stereo, 
kinda swarmish, sure sounds good, all class d, (now). There are no tube amps from 350 hz down, only up, and that varies in the summer months.
Love class d amps, and tubes though, just crazy good.

I also have huge french doors, with heavy curtains, swung open bass goes away, doesn't bounce back into the room

A note: I been using servo units, I just can't get use to it. different story.
All most finished on some 8" LS MB Narrow, baffle SATs. Phase plugs too.

Regards