If your formal study began, as did mine, with 18th-century-style triads as the standard of good piano sound, then you probably grew up, as I did, inflexibly committed to those sounds as the only "true" music.
My students, begun -- most decidedly not as I was -- on 20th-century sounds, are shocked when I tell them that I was an adult before I could tolerate the chromatic pieces in Bartok's Mikrokosmos. Diminished triads were, to my ear, streng verboten, no matter who wrote them. If it was Bach or Beethoven I merely added the missing tone to turn the offending diminished triad into a dominant seventh chord. None of my teachers caught me at it, can you believe it!
The fact of the matter is that the equally tempered piano does not produce the right resonance for 18th-century triads. But, ironically, if raised on music written for the modern instrument, the ear is adaptable and will be open to sounds that approximate various tunings. My students enjoy all kinds of sounds without the distaste that plagued me for so long as a young player.
First rule: Be alive in your time!
