Edgard Varèse’s Ionisation may have stuck to a traditional format, but it broke almost every other mold one might think of. The piece, composed back in 1931, is “a rigorously organized discourse for 13 percussionists playing on 40 instruments, and nothing else”; it employed “timbre, texture and density, rather than melody and harmony, as organizational tools”; and it “dramatically raised the bar for virtuosity among percussionists,” in terms of both dexterity and command of complex rhythms.