As one of the jewels in this year’s program by the Sydney Symphony Orchestra, Claude Debussy’s Pelléas et Mélisande, rarely performed in Australia, has finally returned to the Sydney Opera House. This is not the first time that the SSO has ventured into opera. Judiciously, though, it never competes directly with the national company, selecting repertoire neglected by OA. In 2014, it performed Elektra by Richard Strauss, to critical acclaim, followed by Richard Wagner’s Tristan und Isolde a year later. Later this season, Béla Bartók’s Bluebeard’s Castle will be on the programme.