From its opening vocal salvo, Domingo’s thrilling account of Lehar’s “Gern hab ich die Frau’n gekuesst” from Paganini, through Netrebko’s swirling Gypsy rendition of “Heia in den Bergen” (from Emmerich Kálmán’s Die Csárdásfürstin) to Villazón’s heart-breaking “Dein ist mein ganzes Herz” (Lehar’s Land of Smiles), the program is a welcome reminder of the glittering lost world of operetta.