@stereo
I am starting with one sub and if I feel it isn’t enough, I will get another.
Couple of things, I also just got an SB2000 pro
reason being its small, app 14" x 14" and a 12" driver with good response.
I run a distributed base setup 3 subs in a well treated room for
music only, got tired of rebuilding the failure prone plate amps
so pu a new SB 2000 pro, good specs and it works very well.
The app negates the need for a flashlight and looking at things upside down so a plus.
Regarding 1 sub in a room well it depends on the room as to
just how things will work out and naturally your expectations.
I think I'm now a the point in my room where the bass is tight
balanced without much in the way of room modes.
I should add that even in my treated room I use a very simple DSP sub program to decrease inevitable room mode peaks
and that did the trick.
Good luck