the NSR Sonic Research D-3 was the best by far in any sealed enclosure I have ever heard,for a loudspeaker under 4ft tall to play cleanly below the range of any insrument which is a grand piano I believe around 27hz that is saying a lot, Hyperior,von SCH vr4mk2 are muddy in compare, with the patented APL system and this speaker is 93db efficient and disappears in the room.
On the east cost you can get a listen at http://hifidelityaudio.com I have mine on order this is the best loudspeaker I have ever heard in the $5k range
and I have heard a lot.