This retiring Italian conductor had a serious CV, serving as Leonard Bernstein's assistant conductor in New York before moving on to a career as a principal conductor at Milan's La Scala (and then taking the music directorship of the Berlin Philharmonic). Though deeply familiar with the core Romantic repertoire—his first mixed-orchestra Mahler cycle is a top entrant in that field—he was an experimenter, too, pushing orchestras to address contemporary works. His sense of adventure was likely what made him such a good long-term collaborator for the wildly independent soloist Martha Argerich.