Best speaker/system piano concerts

+1 on ATC, especially if you like to listen at fairly realistic volumes.  

Magico A3s with Pass 350.8 would give what you are looking for if you got the cash.Enjoy!!

Right now, right here, listening to Cyrus Chestnut playing live an Steinway & Sons piano with First Watt F5 (clones) power amps plus Zu Audio Druid Mk IV loudspeakers. Lovely and lively piano sound.

I would also plump for the ATC 150's as I had a pair of the 100s until a couple of year ago when I had to give up my full rig and move to headphones when my wife fell ill and we had to move and now have people on all sides of us. The ATCs are the most natural sounding dynamic speaker I have heard with the clarity of an electostatic and the untramelled power of a pair of subs. I am quite sure you would be delighted with them. As I don't know what your front end is though if you wanted to upgrade that then you would have saved yourself a fortune through not having to buy an amp. Good luck I wish I was in your shoes.

"Large Magneplanar speakers and a Pass X350.8 should give you the power and scale you seek."

     Plus one for dweller's recommendation.  You may want to audition with and without a good tube preamp to best tailor the sound to your speciific tastes.
     Both the new and used 3.x and 20.x Magnepans are excellent for life-like piano reproduction but may not produce the ultimate in powerful and dynamic bass.
     If you prefer state of the art from top to bottom, add this if you have the room:

http://www.theabsolutesound.com/articles/audiokinesis-swarm-subwoofer-system/

     With your large budget, you can afford the extra $2,500 and create a world class system.  I honestly don't know of a system that would sound better.  If I could afford it, this is definitely what I would purchase.

Best wishes,
   Tim