When I had my Advents, with the first Counterpoint, before my Vandersteens, I had a 15” down-firing non-powered sub. (Our favorite brand: DAK!)
The room was small but it helped fill that void. Also made a nice amp stand between my speakers (I had the rack on one side then).
Reproducing bass in a small room is like a short-scale guitar. The sound is the right pitch but the long scale has do much more “meat” to it.
The waveforms of low frequencies are long, and in a small room they are reflecting back onto themselves before they’ve fully developed.
Adding more/larger drivers and power plus room EQ all help but put the same unaltered system in a larger room and the bass “appears” and sounds more natural. It’s not over-amplified and being stuffed down your throat.
Sonetimes, using the same room but setting up on a different wall can make an improvement.
The room is as big a part of a good system as the speakers are.