Best speaker/system piano concerts

Any speaker that is free of artifacts and has enough power behind it will do the job. You can't build a speaker that favors a certain instrument- that is like making a speaker that favors a certain kind of musical taste. Speakers don't care about that, they are a collection of parts that make sound and can't express taste on their own. This however is the most persistent speaker myth in the world.
IOW a speaker that is really good at piano will be really good at black metal, jazz, classical and Chinese pipa.

To reproduce pianos, like an orchestra or modern rock band, you need to make sound pressure without distortion or coloration; there needs to be enough clean power driving the speaker to do the job. If your electronics have issues, a good speaker will simply reveal that. IOW you need a good amp too, and amps don't have any taste either.

I couldn't agree more atmosphere. It kills me reading about folks wanting a speaker that is good for this or that.  This myth is long standing for sure and just silly.

Aside from wanting a speaker that is good for this or that I have to say that I would be loath to find out that a speaker system I was interested in was peviously owned by someone who was into heavy metal music. Reason being that the music played by these bands has so much intentional distortion put into the signal by way of fuzz boxes and other electronica that instead of saying what kind of music they were good for if thinking of buying used the first thing I ask is what kind of music they were used to playing. If classical then it is usually safe to buy because classical is the least distorted music generally on carriers. I have had the misfortune to go to a friends house to listen to a pair of studio monitors that were previously used for rock use and had to tell him his woofers were gubbed due to high volume distortion and it cost him two new drivers.

Any kind of music including piano can damage a speaker if the speaker is abused in some way. I wouldn't blame that on rock.

I play electric guitar frequently, putting distortion from various tube amps through guitar speakers in open back cabinets...I also play cleanly through the same rigs...these things should last for several decades as others I've owned have. I also have some old KLH Model 20s from a compact system I bought in 1970 or something (my first great sounding stereo) and they still sound great (relegated to a garage system). So there.