Speakers that can reveal orchestral instruments' positions

iopscrl:  "Not only pinpoint imaging across the space in front of me, but I could hear depth and height !  I could hear fingers moving up and down the neck of a standing bass.  I could hear the relative locations of a trumpet bell, and the mouth of a tenor saxophone. Each occupied distinct space that could be identified as they played in unison. "

That perception of fingers moving up and down the neck of the bass would be your brain filling in information that does not exist. Your brain knows enough about how that bass is played to translate audio clues into a perception of what is happening. Our brains can do a lot to fill in information that we don't have based on prior knowledge. It does work better when we get rid of the other chafe.

I would agree that the most important factor is the recording quality. From my collection, The Power of the Orchestra, Moussorgsky, A night ..., Pictures ... (LP, reissue) images much better than most. Definitely I can hear the depth. The problem is, not many recordings are that good.

My room is not treated. I might try to improve the room treatment.

@ihcho As I posted above, YES, your ROOM is the most important element of any sound system.

Of course the quality of the recording is important.  Direct-to-Disc recordings from Sheffield Labs and others are about as good as it gets.  Decca as well, and some above mention many others.

I stand by my suggestion: adjust your room, get some good recordings, and then try Magneplanars last.

Cheers!

This is a heavy duty topic. Icho, I also at one time owned Divas. You loved them because they were dipole linear arrays. But, you were right to get rid of them. They were very fragile and hard on amplifiers. But there are good examples available today. Magnepans on the less expensive side and Sound Labs at the higher end. The Sound Labs are IMHO the best speaker made today. 
Dipole linear arrays image better then any other types of loudspeaker for several reasons. Because of their radiation pattern they in part take the room out of the equation. They produce a more realistically sized sound stage and project power better. Sound Labs are one way ESLs. No crossover, less distortion and better transient response. They capture detail like no other loudspeaker. 
Getting the very best imaging out of any system is a difficult proposition.
The problem is that speakers of the same model will have slightly different frequency response curves. It is impossible to make them identical. Then they occupy different positions in the room which increases these variations. We locate sounds by phase and volume. If certain frequencies vary from one side to the other you smear the image.
This is where digital room control comes in. You test the frequency response of each loudspeaker at the listening position. The computer then calculates mirror image filters for each speaker bringing everything to dead flat. Then you can overlay any frequency response curve you like. A set of corrected ESLs is a thing to behold. It also makes you want to murder a bunch of recording engineers. Older classical music is usually wonderfully recorded. Studio popular music is usually a disaster.
Live recordings are generally better but they are taken off the soundboard and are subject to human fiddling. Jazz is generally better again live recordings rule. Pop and Rock recordings you simply have to accept the fact that they are more like works of art rather than duplicating a live performance. It comes down to whether or not you like the experience not whether or not you feel as if you are at a live performance. It is interesting that when you watch a great concert video the sonic image does not matter as much. Vision always rules.