@bdp24 nails it as far as woofer size and how that should be thought of. An 18 inch driver will move very little as compared to a 10" driver producing the same output. I'm using 18's in my system and they barely move for most playback levels. I'm not saying everyone should cram 18" drivers into large cabinets into their living room, but larger drivers, if chosen correctly and placed in the correct cabinets, can be very musical and accurate.
Near field subs
I watched Paul from PS Audio tell about near field subs & thought you folks might like it.