Giuseppe Verdi’s Il Trovatore is a legendary opera that returns often to the Chorégies d'Orange; older opera fans still remember the famous 1972 production featuring Montserrat Caballé at her zenith, the sonorous Lando Bartolini, the hair-raising Irina Arkhipova and thoroughbred Piero Cappuccilli in the principal roles. In 2015, the star for the evening is Roberto Alagna, who has appeared regularly on the stage of the Théâtre Antique since 1993, but who...