I recently purchased a CD of Horowitz playing Schumann Kinderszenen, the Op 17 Fantaisie and the Arabeske. His performance of the last movement of Kinderszenen, “Der Dichter spricht” is worth twice the price of the CD, just beautiful.
The problem I have is that this CD was obviously made from different takes, and on some of the takes there are unisons that are noticeably and distractingly (to me) out of tune. This is Horowitz, for gods sake. You mean nobody noticed?!
This confirms my experience that very few people, including concert pianists, truly know what a piano should sound like. I know that is heresy, but how can you otherwise explain how many out of tune pianos get recorded?