Best speaker/system piano concerts

How about speakers designed by a Piano maker: the Bosendorfer VC7

https://www.dagogo.com/bosendorfer-vc-7-floorstanding-speaker-review/

I haven't heard these models but they are well regarded for their rendition of piano. Other speakers I'd consider are the large Tannoy legacy models, Spendor Classic 100s and Harbeth M40.2s. The latter two reproduce piano much better than most speakers I've encountered. I have to disagree with the advice to avoid polypropylene. Some of the most accurate speakers I've heard use polypropylene cones. Their combination of stiffness, mass, and self-damping properties is competitive with some of the most exotic diaphragm materials. 

As for amps, I haven't heard any that produce more realistic piano tones than those from Yamaha. With your budget I'd consider the A-S3000 or A-S2100. I'm not claiming there isn't better out there, just that I haven't come across them.

Aside from the investment in the speakers and the associated gear, you need to make sure the speakers are set up properly in the room and the room acoustics are properly selected. As Wolf said, many "good" systems can reproduce the piano but in my experience, recreating the soundstage that can accurately reflect the size and the location of the piano is a bigger challenge. Furthermore, the "sound" of piano can vary significantly depending on how its recorded, live or in the studio, and more specifically where the microphone(s) are placed. You'll find on the same recording, some speakers push the piano to the back of the soundstage and others bring it to the front. With that sort of cash layout, you just need to listen to different systems and decide which one resembles the "real" sound of piano better than others, in our room and to your ears. My 2 cents.

I would look more at the front end source.  You want something that can communicate with the rest of your system but has a natural tone with long, slow note decay that will let the notes just linger to give you the natural wood of the piano and provide the soundstage front to back dimension.

Happy Listening. 

"Personally, I do not like what warm sounding equipment does to the sound of a piano. Warmth is wonderful on vocals, guitars and certain instruments, but it beats against the stretched overtones of a piano. The overtones in a piano occur at slightly higher than harmonic ratios, and these create beat notes with the exact integer ratios produced by electronic equipment (and speakers). Too much harmonic distortion will make a piano sound out of tune."

That is quote from John Siau -  Director of Engineering in Benchmark Media Systems, Inc.