I liked the Silverline Prelude floorstander's (single port) that I listened to years ago.
They sounded like a good stand mount (in that the music did not seem to obviously come from the speakers) with tight/defined bass and a large soundstage.
Now they have the Prelude Plus floorstander, which is said to be an improvement.
Unfortunately the Plus retails for $2K and I've only seen one used pair for sale (year, or so, ago).
Not certain if the later version would be OK in a 12X14, but assume that the dealer (Underwood?) would be able to advise on such.
Funny that 2 posts recommending them were deleted.
DeKay