The evening was more bouffe than opera. The microphones crumped as the hostess, Beverly Sills, made a few remarks. She had to deliver them again and again until the TV cameras got it right. Then the $150-a-ticket audience was asked to applaud uproariously—for an empty stage. "We should get out of here by 2:30 in the morning," Sills cracked.

Had this been an ordinary concert, the audience might have stomped out. But the taping of the annual Gala of Stars benefit for PBS at Carnegie Hall, to be aired March 22, was a resounding smash. Victor Borge, Gelsey Kirkland, Isaac Stern and Jean-Pierre Rampal all did turns in honor of the concert hall's 90th birthday. What was Liza Minnelli doing in such company? "What's the difference?" asked Liza, the only performer ever to sell out Carnegie Hall for 11 straight solo performances. "It's all show business."