I have read several times that some acoustic music , such as piano, acoustic guitar, double bass etc, as well as the human voice, are amongst the most challenging to reproduce from a recording.
Mike Moffat has said that he likes Bluegrass music, and I am sure that this is a very good test of any audio system.
I listen to quite a lot of acoustic music, and I am very happy with the sound from my Yggy-based system.
In my opinion, nothing beats live music, and I went to my first acoustic gig in 2 years recently.
It was fantastic- Banjo, fiddle, mandolin and guitar.
A friend of mine sent me a CD which he recorded in a small professional recording studio of him playing a Grand Piano, unaccompanied.
It sounds almost 'real' to me and is one of my most treasured CDs. I think there are only 5 in existence!
Several years ago I met someone who had a Steinway Lyngdorf audio system ( made in Denmark)
It cost about £200k!
https://steinwaylyngdorf.com/steinwaylyngdorf/
The company claim that from behind an acoustically transparent curtain, the sound of a grand piano played though their system is indistinguishable from the real thing and that listeners cannot reliably identify which is which.
I don't have the money, or motivation to test that claim