Gayden Wren's version of Dickens' story grew from a clever conceit: He took songs from the Savoy duo's operettas and fitted them with new texts to tell the Christmas Carol story.

Thus "Tit-Willow" from The Mikado became "Bah Humbug," and "Three little maids who, all unwary, come from a ladies' seminary," became "Three little ghosts who, dark and scary, come from a nearby cemetery."

Those who left missed some fascinating work on the famous "Queen Mab" Scherzo—and a moment of Levine humor. He was urging the orchestra for more lightness, to keep the music "up in the air." "When I want weight in Wagner, I have the body language to ask for it," Levine said. "It's a little harder for me to get lightness."