Watch Yuja Wang do her Lang Lang shtick

John Borstlap says:

Erwin (here above) is absolutely right. When I studied the piano, I did not believe those toucher stories too, untill I experienced it myself. With a good piano, i.e. with a tight mechanical system, the transportation tract reacts to all nuances of tension. The energy with which the key is struck, is transported through the system and is capable of influencing and changing the colour. Older pianos are often better at responding. I remember playing at a Gaveau from 1880 with double string layers, where the tone began to ‘sing’ through the instrument, vibrations setting other vibrations in motion. Many modern instruments are too cold and too mechanical and often lack this possibility of shading.

With the right toucher you can imitate a harpsichord sound as well as a warm, velvet romantic sound, and everything in between, all according to how the instrument is handled. It is an old tradition. For instance, Debussy’s piano playing, which was, according to the stories, magical, was characterized by low-holding hands, almost flat, which softly sank into the keyboard as if massaging the keys, and he could make the piano sound as if there were no hammers at all. Stravinksy played the keyborard with a spiky toucher, in accordance with his music. And Sally plays in the way a butcher chops his steaks and the piano reacts accordingly.