BEST LOW VOLUME FULL RANGE SPEAKERS?

Once again I want to mention the Von schweikert dB99's.
They have a powered system for the 10" drivers that are designed to assist ones own amp and they are spec'd down to 20 Hz. They are 99dB efficient which helps with nice dynamics even at low volume, they have the size and looks that will work and cost new what he is willing to pay.
I can't say I've heard them but have read some great reviews on them and would like to.

Electrostatics!

Ah, now here in Krellm7's recommendation I have FINALLY found a suggested speaker I will agree with. Electrostatics!

That being said, most electrostatics do not meet the 20 Hz bass/no subwoofer requirement, and they certainly do not meet the WAF requirement. But, no matter how much we hope, pray, beg, borrow, or spend, there is no perfect speaker in the world. Regardless of price range. You do as well as you can, and I think the electrostatics may come closest to what you are searching for sonicwise.

The rest of what I say will cause a lot of people to come out of the woodwork after me with the most vehement opposition... What I hear when I listen to electrostatics is far, far different from how the "conventional wisdom" describes them. Not ultra fast, ultra open, ultra detailed, ultra neutral, or any of the ultra terms normally thrown out there. NONE of that. I hear rich, warm, relaxed, and easy to listen to. Especially at low volumes. Rich and warm above all else, but then, from what we were angling for in a lot of our posts is exactly that. What I call the "pipe and slippers" sound. So, I think that the electrostatic recommendation is particularly brilliant with the aforementioned caveats.

Trelja,
That is an apt description of the electrostatic sound. They will sound that way if you tell them to with your choice of preamp and amplifier. Like em, love em, or hate em the electrostats are telling of the equipment they are connected to.
If you are going to smoke your pipe (or anything else around them) do keep in mind that the panels will build up a residue that can't be removed. They will sound muted and congested (becasue they are physically congested with tar) because teh woofer is relatively unaffected while the panel is opperating at a far reduced efficency.

If you want truly full range at low volumes you should try the new Vandersteen Quatro. It's amazing! You'll have the ability to tune the bass to your preference in addition to getting the best imaging and natural sound possible for the price.
Good luck in your search!