“The gaudiest event of the opera season in Europe, La Scala’s opener on Dec. 7 was a sublime new version of Tristan und Isolde directed by Patrice Chéreau under the baton of the house’s new principal guest conductor, Daniel Barenboim. ….. Mr. Barenboim, who knows this opera as well as anyone, drew rich, densely textured, multilayered sounds from his players.’’ New York Times