Do hi-end DACs offer true value or diminishing return...

Ok i understand you point now...

You are right for sure... The quality of classical recordings depend on microphone expertise by design and by the way they are used...

You are right for the "work routines"...

Simply, every reproduction audio systems sound veiled, bright, and un-natural.

Even many original recordings have veils/brightness depends on quality of microphones and recording machines. The idea of mic is similar to loudspeakers. Few great sounding mics are made by people who had made mics all their life in 1930~60's and found some work routines for good sound. Still they didn't know what makes good sounds. They just knew some work routines.   Alex/Wavetouch

I wish the quality of recording for live classic music can be enhanced. Often time, you could observe only one microphone hanging from the ceiling in the middle of stage is used to record the entire orchestra.  That is simply inadequate for hi fidelity sound recording and reproduction.  Periodically, if you found multiple microphones were placed for each group of instruments and individuals, the quality of recording usually turns out much better in terms of separation, soundstage and clarity.  

OP,

By one microphone hanging… I assume you actually mean two… stereo.
 

 But!  Multi-mixing completely screws up the acoutics of the space and hence the essence of the orchestra… when playing multiple instrument. Completely destroys the acoustics.

I have had season tickets to the symphony for over ten years. This is how I learned what real acoustic music sounds like (along with some smaller venue jazz and classical). I have spent hours carefully listening to how the reflections from the venue and the multiple instrument interact to cause the experience. The careful location of the different instruments and the composer has orchestrated those frequently to form huge waves of intense sound that can wash from left to right or otherwise complex pattern. 
 

The very worst recordings I have heard have been those multimiked jobs, the very best late 1950’s with two microphones.

2019 Grammy best engineering award was given to three engineers Shawn Murphy et al. for Shostakovich: Symphonies Nos. 4 & 11 performed by Boston Symphony Orchestra conducted by Andris Nelsons. You could see how the multiple microphones of different types were placed in the clip.

https://www.youtube.com/watch?v=u8hF_NVqCtg

Beethoven sym. 9 performed by Chicago Symphony Orchestra and Riccardo Muti also used multiple microphones of different types. There must be good reasons behind why the award winning recording engineering project and famous symphone orchestra performance uses multimiking.

Very interesting post! Thanks very much...