The piano remakes the music

On Slate, Jan Swafford visits the historical piano museum run by Michael and Patricia Frederick in Ashburnham, MA, and rediscovers tonal effects in old scores that can't be produced on modern pianos:

http://www.slate.com/id/2245891/pagenum/all/#p2

Among the audio samples, you can compare Debussy's "Feux d'artifices" as played by Arturo Benedetti Michaelangeli on a Steinway with a performance by Virginia Commonwealth University's Dmitri Shteinberg on an 1877-vintage Erard instrument.