Thoughts on the most difficult instruments for speakers to reproduce?

I read this whole thread, and thinking about it, it seems like it's much easier to list instruments that are reproduced successfully by good quality speakers than those that aren't.
I would say sax, trumpet and brass in general are not that hard to get right. Same goes for acoustic guitar, as well as some small percussion instruments like blocks, shakers and bells.
Pianos, violins and other bowed instruments can be dogs to reproduce convincingly. Of course , part of the blame for that goes to the way they are recorded.

Easily , massed symphonic strings .

Cello.
Hearing a cello in a quartet live vs recorded...
The recording never gives the real thing.
Massed violins are another tough one.
Agree about cymbals too.
(one of the able to hear reasons I just bought a $7000 disc player is hearing on a recording the clear sound of the brush hitting the cymbal, then the shimmer sound in response. Instead of the usual smear of noise)

I would chose voices and acoustic instruments, especially piano, violin and trumpets.

Back eons ago I was a rock and roll drummer and with some (but not all) well-recorded ride cymbals, you can "hear" the ping of the stick against the brass and "feel" the timbre of the cymbal vibrating.