The thing about full range drivers is that they aren't.
So if you want to really have fun with them a sub system is a good idea. To that end you might want to look into the Swarm by Audiokinesis, since it can do an excellent job of integrating. The subs are small and meant to be placed directly against the wall. There are four of them; they are meant to be placed asymmetrically in the room. In this way they can break up standing waves in the room, giving you uniform bass to 20Hz without drawing attention to themselves (both sonically and visually). To that latter bit, they should not be run above 80Hz. 80Hz and below is the frequency at which the human ear detects bass only in an omnidirectional way. Its harmonics of the bass instruments that will be played in your Lowthers, causing the soundstage.
The Swarm subs are 1 foot square and 2 feet high; fairly small as subs go yet they go to 20Hz as they are meant to take advantage of the room boundary effect. IOW you can't do the same placement with regular subs as they will draw attention to themselves if placed against the wall, making integration very difficult!
The Swarms have received three Golden Ear Awards, well deserved.