The world premiere of Nico Muhly’s new Baroque-inspired Piano Concerto is surrounded by three other unmissable and underrated works of time-hopping, genre-swapping proto-postmodernism: the cerebral mischief of Paul Hindemith’s raucous Ragtime, based on a theme by J.S. Bach; Edward Elgar’s inventive transcription of Bach’s Fantasia & Fugue in C minor; and Hindemith’s Symphony Mathis der Maler. The last takes a 16th-century artist’s struggles against repression as the basis for a majestic symphonic triptych.