music with clear placement of the instruments.

I'll try to answer Viridian's question:
When I go to concert in good venue and close my eyes, I often hear a clear placement of instruments. I certainly can't tell placement of each 'line' violinist of large symphony orchestra, but able to place small jazz or chamber quartet that performs with no mikes in Minnesota Symphony Hall, Place of Arts(Montreal), Gesu(Montreal).

"A bit off-topic, but when you go to a live concert, and close your eyes, do you hear a very clear placement of the instruments?"

IF a good venue, production and good seats, I hear a soundstage consistent with the perspective from my location, meaning I can focus on any of multiple things going on in different locations at any time.

Perspective changes with location and affects what we hear with our two ears in much the same way as what we see with our two eyes. That's why God gave us two of each!!!!

Love Art Blakey. In that sample and in all jazz recordings of that era, a minimal amount of microphones were used, plus all members of the ensemble were playing together in one room. This technique provided a sense of space and "air" between the instruments. In the recording, the soundstage included the ambience of the room and an accurate reproduction of the location of each musician.

Not so today; multiple mic's are used and positioned close to each instrument...too close IMO. For example in the 50s and 60s the drums may have had only one or two mic's overhead, now-a-days each drum and cymbal gets it's own mic. This technique will make it more difficult to isolate one instrument. Of course there are engineers who know how get that open sound like the old jazz records.

Also, it's now common to record each musician alone in the studio and then combine the ensemble during the mixing process. The engineer can add reverb and other effects to simulate the entire group playing together, but the result will never have the same soundstage as the the early recordings.
Some of today's engineers can work magic and position the musicians in their proper space, but as you've noticed it can be hit or miss. It's the producer and the record label who decide the sonics of the album. You may already know about today's recording techniques, but I thought I would mention it anyway.

I just picked up a new Pat Metheny CD and the cymbals are positioned in front of Pat, and the drums sound like they're right next to him. And don't get me started on compression.