The snow outside did not stop them. As the audience filled for the arts, the seats of the Staller Center on Saturday night, they gazed upon a black grand piano reflecting the blue lights above it. Some were Broadway enthusiasts and others had seen the performer at other locales. As the lights dimmed, the audience clapped softly while her pianist, drummer and cellist walked on to the stage. Then, Audra McDonald took the stage in a black floor-length, sleeveless dress and the soft clap elevated to a roar of applause.