“You are about to enter a world unlike any other.” So begins Canadian pianist Marc-André Hamelin’s introduction to his recording of Morton Feldman’s For Bunita Marcus, a 72-minute solo composition set entirely at the composer’s favoured dynamic level: very, very soft. Feldman was a Jewish-American composer who, like Cage, became a figurehead of the avant-garde, dismantling and reimagining what music was, and what it could be. He’s famous for exploring indeterminacy, and his works are typically very quiet, or as the composer frequently marked his scores, “just about audible”. Hamelin suggests in...