Best speaker design for low to mid volume?

I'm not asking brand etc. I have a condo that had a listening area (approx 20 ft X 15 ft). I'm looking at floor standers. Generally, should I look for few drivers or more the better? Some speakers are 2 way, 2.5 way, 3 way etc). I listen to everything from classic rock to jazz and classical. This is a 2 channel system. Some tv/movies will be played through speakers as well. I like full bass (not so much the very tight bass sound and too crisp sound I find with Klipsch). Please chime in...sitting area approx 7 to 10 feet in front of system. I'm not looking for bookshelf speakers (WAF).
IMHO, every designer takes his chosen technological elements and then finetunes them/voices them to make them as good as he can given the technology he uses and the budget he has set for production. There are great horns, great 3-cone, 3-way, 2-way, panel. Also depends on your budget. $500, $1500, $3500, $5-10K, 20K, 50K, etc...that also makes an enormous difference.

Because there are too many way to design speakers well...i would say the one feature i do find in common with nearly all great quality of the enclosure. Very solid, no vibration, sometimes inert materials (resin-impregnated woods), aluminum frames...these materials usually speak to someone who spent time designing, is trying to create an inert box to be able then more consistently deliver sound through the cones, and create a more transparent sound. good luck. hope that was [a little] helpful...ask away with further questions.
generally a small speaker plays at lower volumes better than a larger speaker.
Not always true.. but in a broad catagory way..
I like my big Magnepan 3.6 playing at low volumes..
The most perfect low volume mid sized speaker is an electrostatic IMO. Especially Quads, or martin Logan.
In general I find that more efficient speakers are also better at low volume than speakers of lower efficiency. A minimal crossover might be the reason for that (more technically able A'goners correct me if I am wrong on that).

Also contributing to the quality of low level listening will be your amp. I will let others describe why this is and what you will want to look for in an amp. But in my experience, when I plugged in my recently acquired Butler 2250 one of the improvements I got was in terms of low volume listening.
In general, the more efficient a speaker is the better will play at lower volumes. Consequently, horns will be the best choice. Since you can sit 10 feet away from the speakers Avantgarde UNO comes to my mind though might not have a too high WAF.

Another way to get good sound at low volumes is to use a subwoofer. This is because in IMO one will not be able to get a healthy bass al low volumes unless he/she goes for very expensive speakers (often not even then). Since you are not interested in getting bookshelf's speakers you should get some smaller floor standers with a subwoofer. (As Elizabeth commented above smaller speakers do generally play better than larger ones at low levels).
Well there you, every answer is correct and no one agrees. There is no answer as far as one design being better at low volume. You'd probably be better off asking for the brand. I've built alot....alot of speakers. Generally if you can find a speaker that has a slight rise in the frequency curve in the lower region, then stays accurate through out the rest of the frequency range, you will have a speaker that sounds nice at low volumes.
Planars like Magnepan are fantastic at low volume. full range electrostatic speakers like the Quads also.

Box/dynamic designs that use rigid low mass materials (like paper) for woofer cones can be similarly very good also. Triangle is the line that comes to mind as an example.

I find the newer OHM Walsh speakers I also use can also be similarly quite good in a different way at low volume with the right amp and electronics in front of them, and these can also go as loud as needed with no signs of stress or dynamic compression as well with proper amplification, which is a big reason I prefer these over most planars or electrostats in the same price range.
Tim - too true!!! ;) although you and i did agree in our opening statements...many ways in speaker design to get there!

That said, i also would 2nd nvp's statements about subwoofer for low volume playing. I run Wilson X1/Grand Slamms...and like every single Grand Slamm or Alexandria owner i know...i run a big subwoofer in parallel...when i play at literally volume 1 on my system...the sub makes a big [positive] difference. you heard a very, very satsifying but level, controlled 'thump' even at these soft levels that means you feel like you've lost nothing at all when playing in the early am and dont wish to wake up the house.
one man's experience.
Controlled dispersion designs sound better at low levels since they do not flood the listening space and direct SPL at listener thus better sound at lower levels.
Quad ESLs. I have the 988, and it's magical at low volume (and restricted low frequency extension is actually a blessing in a condo). Not exactly pretty, tho, if WAF is an issue. The Audio Physic Virgos I once owned were good at low volumes, and beautiful in maple. A bargain used if you can find them in good condition.
A factor too few speaker manufacturers take into account, in my opinion. Many of us live very close to neighbours, with thin walls and want to be "neighbourly".

I agree that high sensitivity is often a prerequisite and can name a number of higher sensitivity speakers that sound good at low volume, Harbeth, Devore Fidelity, Living Voice and my own Daedalus. I can also think of well known brands that need the wick turning up, to sound their best, particularly Focal and B and W, neither of which I can say I really enjoy.
Contrary to the experience of others, with my Quad 63's I found that they only seemed to come alive at moderate volumes. At low volume they were not very engaging. My present boxes which are 6db more efficient seem to do a better job when driven by medium power amps. I sense but do not know for certain that the more efficient the speaker the better the low volume performance.
So the number of drivers really do not matter as much? It's the overall frequency of the speaker. I was considering the tekton Lores or Zu Omens. However, the B&W 603 towers get great reviews. The Tektons and the Zus do have a money back guarantee. The tektons come with optional grills.
Hi Aberyclark,
It is not cast in stone, but generally multiple drivers give you higher sensitivity. There are many designs that don't need multiple drivers to give that sensitivity. Sensitivity on its own does not improve the sound of a speaker at low volume, it just means that you don't need much power to drive it. On the other hand. I do believe that sensitivity almost always improves dynamics. This is in general, there are lowerer sensitive speakers that with the right power can be very dynamic. Its just most high sensitivity speakers are dynamic.
03-23-12: Timlub
"It is not cast in stone, but generally multiple drivers give you higher sensitivity."

Is that true? When I think of Hi Sensitivity speakers I think of only 1 or 2 drivers. When I see multi drivers I think power sucking, sensitivity lowering crossovers.
Similar size room as yours and also in a condo.
My Eminent Technology LFT8 speakers sound great and balanced at low volumes. One of the things I like best about them. would think other planar speakers would be similiar . Bass is excellent on these speakers and is not lightweight. Though they do need some power I am using a Pass x150.
It seems many european manufacturers mentioned have quite a selection of very efficient and low volume friendly speakers. I wonder if it is due to the generally "smaller" living spaces that is so common in Europe?