When a production as deeply unpopular as Mary Zimmerman's "rehearsal studio" staging of Bellini's La sonnambula returns to the stage, you know there can only be one explanation: star vehicle. Diana Damrau occasions the revival and, happily, has the goods to transcend her surroundings; we also hear good things about Javier Camarena, the tenor portraying Elvino. Marco Armiliato conducts.