Excuse me, can I ask you what are well-recorded string quartets and small orchestral music for you? If it's not difficult for you, give a name or a link to the source.
Even these two well-recorded quartets cannot frighten and load more than 30% of the potential of these three excellent phones (NDH 30, ADX5000, AKG K812) There is no significant difference in sound on such examples. This is not the kind of music and recording on which you can test such high-level headphones.
As a rule, such music are recorded on a stereo pair with standard placements and standard sound processing. There can be no talk of any multi-layered sound, bass features or three-dimensional space, refinement and delicacy of sound.
You describe the ADX5000 as a headphone that adds delicacy to the high frequencies and the dimension that is lacking in the NDH 30 compared to the ADX5000. Note - ADX5000 ADDS to the original audio recording what is not in it...
I think you need to spend more time with NDH 30 listening to more complex and technically complex and mixed music. In order to understand what really are the differences between these three phones.
The ADX5000 and AKG K812 are excellent headphones, I've spent a lot of time listening and working with them. And I always have them on hand in my neighboring studio. BUT they are excellent not for the money for which they are sold.
NDH 30 are new headphones with a new design and a fundamentally different approach to sound playback. This approach is called the exact but musical reproduction of the sound recording as it is in the original. And this approach is now gaining momentum and will soon be in trend.
In order to truly understand and feel this, you will need to spend more time with them.
By the way, on these two recordings, NDH 30 plays high frequencies so cleanly and delicately and just as voluminously and three-dimensionally - that more than that would already be
unnatural and indecent)))
Takacs Quartet - Hough, Dutilleux, Ravel_String Quartets (2023) [24-96]
Talich Quartet - Debussy, Ravel- String Quartets (2012) [24-96]