One of the legacies of Pierre Audi’s tenure as director of the Aix-en-Provence Festival is the festival’s commitment to a continuous challenging of what opera can mean. His provocations extended from calling filmic versions of Stravinsky’s ballets operas, to a rendition of Mahler’s Symphony No.2 directed by Romeo Castellucci, or even, last season, a musical of William Kentridge’s “The Great {…}