It may sound hyperbolic, but without Jack Irons, the Red Hot Chili Peppers and Pearl Jam may never have come to exist. The 59-year-old drummer was key to the formation of both of those Rock and Roll Hall of Fame-inducted bands, thanks to lifelong friendships with musicians such as Flea, Anthony Kiedis and Alain Johannes, and to his chance handoff of a 1990 instrumental, pre-Pearl Jam demo tape to a then-unknown San Diego singer named Eddie Vedder, who was afterward invited to join that band within a matter of weeks. In recent years, Irons has released a host of largely instrumental music on his own, boiling down the essence of his rhythmic prowess into tracks that at times recall the spookier side of trip-hop, the precision cool of Kraftwerk and the spaced-out syncopation of Can. On March ...