I have a two channel system with a pair of SS8's. They sit on an open wall in a large open main floor with 14 foot ceilings. That equates to over 10,000 cubic feet of space, not counting the rooms the space opens into. I know some folks that think adding subs in a two channel system is a sin, that my speakers or amp are not up to task. But they fail to understand what space does to bass. Just because you have speakers that are spec'd at 25Hz to 20KHz +- 3dB does not meant that they will play 25Hz - 20KHz +- 3dB in your room.
I added two 12" subs to augment the 25 to 35Hz range. I've also added acoustic treatments. Four bass traps, two 4 footers stacked in corner that one speaker is nearest to, and some wall treatments. SVS and Rythmic have told me I really need two 15" subs for that amount of space. For a two channel system with my frequency playback requirements. Now much depends on the music I play. I consult a music chart to see the lowest frequency instruments play and I sweep my room to measure what range I may be missing. (I like pipe organ music). Most music I play, the subs don't even respond.
You want to use speakers for movies which can have frequencies well below musical instruments. Of course it would depend on the movies you watch too.
Now I can box my speakers into corners which will magnify the bass, but that causes its own set of issues. Boxed by corners, even with stacked bass traps in corners, I would have to put them so far into the room that seating would be in the foyer.
My point is don't expect any floor standing speaker to do the job of playing at the bass levels you need depending on space and placement in the room.