It is almost a universal truth that Subwoofers made by brands who specialize in audio Speakers will not be very good.
SVS started with Subs; they happen to do Speakers, now. But the Subs are generally well regarded.
Perhaps the only exceptions to what I wrote above may be Martin Logan (Dynamo, iirc) and Paradigm (Defiance). Some of the newer Klipsch Subs seem to be measuring well compared to those of the past. On the other hand, most of these that are worthwhile are also fairly expensive.
FWIW, I have never heard a single person say that Dali makes a decent Sub.
Happy hunting.
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OH, is your room closed off or open to rest of home? This can make a big difference in how the Sub interacts with your space. In a closed room with your square footage, a sealed sub will work well regardless of ceiling height (unless you are in a grain silo!), however in an open room/floor plan, that Sealed Sub will not perform as well as a Ported Sub can.