Mozart cobbled together his “Haffner” Symphony from music he wrote to celebrate the young Sigmund Haffner’s ascension to nobility, instructing musicians to play as “as fast as possible” in the thrilling finale. After the symphony, FWSO music director Robert Spano conducts American composer Steven Stucky’s The Classical Style: An Opera (of Sorts), a comedy in which Mozart is a character alongside other famous composers like Beethoven and Haydn, all portrayed by the talented Cafritz Young Artists of Washington National Opera.