Charles Dutoit has conducted the Philadelphia Orchestra hundreds of times, and this fall, with the venerable band still lacking a music director to replace Christoph Eschenbach, he becomes the de facto artistic leader of the organization. “He arrives not merely as conservator but as active restorer, with a stated purpose of initiating the orchestra’s newest members, who might not have been born in 1980 when [Eugene] Ormandy finished his sound-building days.”