Hi Clay,
Thanks for your kind words and detailed response.
SP Technology makes a speaker called the Timepiece that comes to mind. It combines a waveguide-loaded tweeter and a woofer that goes pretty deep and solid. The waveguide gives good radiation pattern control which is desireable in many applications. In a small space where the first reflections arrive fairly early a consistent radiation pattern means the early-arriving reflections are less likely to color the sound. And the relatively narrow pattern (compared to direct radiators) is conducive to good imaging - though at the expense of some ambient richness; it's a tradeoff. The SP Tech speakers have a fairly flat frequency response (somewhat reminiscent of a good studio monitor), and some people prefer a gently downward-sloping response. I must confess that I haven't heard them at low volume levels.
Electrostats excel at low and medium volume levels, but from your description of where the speakers will be placed (pretty much up against a wall, unless I misunderstood you) I don't think they'd be practical.
One of the best-imaging speaker lines I know of is Green Mountain Audio, but again they like some space around them to really make their magic happen. I've heard them sound less than full in the lower midrange region, but that may not be applicable to current models.
Harbeth makes some very relaxing, warmish speakers that you might consider. Warm is good at low and medium volume levels. The Super HL-5 comes to mind.
A company called Tonain Labs makes a very nice speaker for low to medium volume levels called the TL-D1. It's way below your price range but is in my opinion a real contender. I have some familiarity with the almost-full-range driver used, and it will lose articulation if pushed to do large, high-output bass excursions. Tony's a great guy and he'll level with you.
An Italian company called S.A.P. makes a lovely little speaker called the Trio that I think is near your price range. Its driver complement looks bizarre but it sure sounds good, including at low volume levels. Can't say that I recall the imaging - I tend to focus on other things.
Finally here's a wierd suggestion but it might be a heck of a lot of fun. Many years ago Altec made a couple of very enjoyable, largish loudspeakers called the Model 14 and Model 19. They show up used from time to time. I recently lost a pair of Model 14's when my store burned down, and miss them all out of proportion to the $750 or so paid for them used. Realistically they aren't imaging champions, but they are very lively sounding (not to imply bright, though). I mention them as a sentimental favorite.
I know this is probably too many to choose among, but presumably you'll narrow down to a shortlist (which may or may not include any of these) and then study those out carefully and if possible audition.
When you audition, as part of the process I suggest you try listening outside the room, through the open doorway with no line-of-sight to the speakers. This way you'll be listening exclusively to the reverberant field. If it still sounds convincing, that's an excellent sign. You may have noticed how live instruments sound convincing from the next room but loudspeakers seldom do. Those that do (assuming they don't screw up elsewhere) are likely to be very enjoyable long-term.
Presently I'm not a dealer for any of these. I may e-mail you separately with a suggestion or two from among models I do sell.
Best of luck to you,
Duke