Francis Poulenc stole the show last night as the Aspen Festival continued in the Kennedy Center Concert Hall. His "Le Bal Masque" was sung by baritone Leslie Guinn with principals of the Aspen Chamber Symphony, wondrously reproducing the dialectic of substance and nonsense that defines Poulenc's sensibility.

Set to Max Jacob's surrealist peoms, "Le Bal Masque" removes the cruel edge from verses like "the ft blind lady with bleeding eyes," embracing them with warm and witty melodies. Its challenges are mostly stylistic, and they can elude many a great singer. These challenges Guinn more than met, using his sweet baritone with elegance and elan. From the whirlwind of the opening send-up bravura through the tango beat of the "Caprice," the Aspen instrumentalists were masters of this elusive idiom, with the violinhs mock melancholy over "The Blind Lady" causing many a knowing smile.

Lighter, louder and far less interesting was the evening's world premiere, a trashy set of Variations for Brass Quintet by Edward Barnes. The sound of raw brass is always impressive, and the American Brass Quintet was in fine form, even adding an appropriate pop timbre to the B-flat trumpet. But no wealth of sounds could rescue this work with its unimaginative tonalities and overpowering dynamics.

The concert also included the Cleveland Quartet in the Piano Quintet in F Minor by Brahms, with pianist Lee Luvisi. The entire program would have looked and sounded better in the Terrace Theater, where most of the audience could have fit comfortably last night.