Thoughts on the most difficult instruments for speakers to reproduce?

Most real instruments sound horrible in most speakers, specially in digital recordings which sound horrible bright, thin, edgy, sometimes not even within the note, like a good $20k hand made Spanish guitar, piano sounds harsh, violins sound thin & harsh, cymbals without extension at all, toms not silky at all, bad bass drum, electric piano without proper decay, well the list goes on and on. 

@glow_worm, I am assuming you are a Miles Davis fan, as am I. A real test for any speaker ( system really ) and an awesome musical experience is Miles's " A Tribute To Jack Johnson ". Could be my favorite of his ( although he has an amazing library ). There are 2 editions I am familiar with. A 1992, and a 2005, both on Sony. I prefer the performance and mix of the 1992 release. If you do not have it, it is a must. Enjoy ! MrD.

As a drummer I am sensitive to acoustic drums on jazz, or singer songwriter records. Cymbals have complexity and air. Not on rock records and for sure not on modern electronic records where samples are the thing, but actual beautiful cymbals at the hand of a sensitive player. When they're right they touch my heart.

Many instrument's sounds are difficult to accurately reproduce but the one that clearly is the most difficult is the piano because of the range, attack of notes and nuances that seems to transcend most other instruments.  I love organ music but I can hardly say that it doesn't sound realistic (except some close to subsonic notes).  If you listen to recorded piano music, it doesn't take a golden ear to tell it's not quite right.

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.