The most perfect of all pianists ever was undoubtedly the Italian Arturo Benedtti Michelangeli. Notoriously difficult and fickle,he pursued a style of piano playing that can be best described as "crystalline". He possessed a truly phenomenal command of the instrument, unmatched by most of his fellow pianists.
Here is an ultra rare video footage from the fifties where one can see the master shortly listen to a student and then play himself.
Arturo Benedetti Michelangeli - Masterclass documentary (1959) - Part IV - YouTube
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