Placing Instrument Separation of Large Ensembles in Recordings

Achieving instrument separation in recordings of large symphony orchestral performances requires a combination of thoughtful microphone placement and effective mixing techniques. This process will involve understanding how different instruments interact within the frequency spectrum and using EQ to carve out space for each instrument. For example, one can boost certain frequencies while cutting others to minimize overlap and enhance clarity. Also, adding delay or reverb to create sense of space and enhance spatial separation like the other gentleman said, etc...

Now it comes down to your system. While your system may not create additional spatial information, it should be capable of preserving and reproducing it satisfactorily in your room. By carefully selecting high-quality recordings with properly captured spatial information, you can play them back on your system and cross-check against video footage (if available) to assess if your system is able to meet the following (but not limited to) aspects:

1. Instruments are properly positioned.
2. The width and depth of the soundscape are consistent with your listening experience.
3. The volume levels of each group of instruments are reproduced properly.
4. The notes from each group of instruments are clearly defined and well-articulated.

Keep in mind that spatial separation may be less pronounced in orchestral performances, as many instruments are often playing simultaneously.

A great example is the 2024 Grammy Award-winning album Contemporary American Composers, performed by the Chicago Symphony Orchestra under conductor Riccardo Muti, with renowned recording engineer David Frost. Listening to tracks 3 and 4, and cross-referencing with available video or images, can serve as an excellent benchmark to evaluate your system’s performance.

You're not supposed to hear individual instruments in orchestral pieces unless they have a solo part.  You want to hear the first violins as a group, not individual violins.  I believe that what most composers, conductors and engineers are aiming to achieve.  Chamber pieces are a different situation.

I hope I haven't misunderstood your point.

I listen exclusively to classical and I am familiar with your streamer.  I don’t know the amp and the 

Orchestral Music is difficult to reproduce.  My own system improved when I added DSP and added a sub.  The DSP help correct for room modes and the way that you describe the blackness of orchestra reproduction in your system this may be an issue.  And Quads are notoriously bass shy speakers so a musical sub will probably help a lot

Consumers are at the mercy of record producers and engineers. As @onhwy61 and @rick_n stated, there are a number of different recording philosophies and techniques, each with it's own resulting sound characteristics.

If you ever come upon any ARK Records LP's, snap 'em up! They were engineered by loudspeaker designer Robert Fulton (Fulton Musical Industries, a/k/a FMI), who recorded local (Minnesota) church choirs and organists. The LP's feature startling-alive sounding recordings, with amazing inner detail. You can hear each individual voice in the choir, for instance. Liquidly-transparent sound, almost as good as a direct-2-disk LP.

Pinpoint separation of instruments in an orchestra doesn't exist in real life. So, arguably, the recordings with the least separation are the most accurate.