But, most unusually for Zurich, the 80-something conductor of Tristan und Isolde, Bernard Haitink, was roundly booed by a large section of the normally placid Swiss audience.
His offence? The last-minute replacement of the scheduled Isolde, Waltraud Meier, by Barbara Schneider-Hofstetter, following "musical differences".
“Haitink and Meier are two exceptional artists and strong personalities, who express their opinions clearly. They couldn't agree on this project,” Joachim Arnold, marketing head of the opera house, diplomatically explained.
*UPDATE* an unofficial record of the incident (booing begins around 3:18):