Context: My teacher and I were playing some AI generated music which included some chords that were quite difficult if not impossible to play. We started speculating about what are the most difficult chords that have been put into music that is expected to be played by a person.
Rachmaninoff notoriously has composed music that includes chords that require a large hand span and a high level of dexterity.
What are the longest and most difficult chords that Rachmaninoff has ever put into one of his songs?
Has anyone else composed a piece with a chord that requires a hand span larger than Rachmaninoff's?