Regarding the X3's, I shouldn't be running subs according to the manufacturer of my integrated. I currently use RCA's spades at one end and resistors on the other inside the RCA jacks. I do not have preouts on my integrated. But I'm told that's a bad idea for many reasons. I need to stop that practice.
The foundation is really important to the music genres we enjoy. The reality starts to set in when I look at the 'big picture'. I picture a speaker with adjustable bass, woofers, preferably, almost certainly self-powered so that my tube integrated only see's the mids and tweets. I know by experience too that my wife likes a very dynamic picture. I do too. The speaker has to play Radiohead, Porcupine Tree, Shiny Toy guns, as well as female vocals, electronica, jazz, blues, and classical if it can pull it off. My experience with classical is that only big speakers with lots of drivers can pull off the scale of classical. Well, maybe horns too. I know most will disagree but that's been my experience.
My room is pretty good. 15' x 19' dedicated with GIK bass traps and acoustic panels at the front, 1st order reflections taken care of, Cement slab, thick carpet, rockwool on one wall, LCR panelboard but a dead back wall as it's nothing but shelving holding vinyl. So no 'live end - dead end'. I don't hear bass issues with any of the speakers in that room not that they don't exist of course.
Swarms are the best way to get a good bass response, fully agree, but I don't have that option. Another reason why I keep thinking that the Legacy Audio Focus XD's seems to check a lot of boxes.