Annual music school benefit concerts, like Catholic University's last night at the Kennedy Center, tend to move at the pace of graduation exercises. Protocol inhibits flair and innovation.

Sometimes something, or someone, though, breaks through the obligatory shackles that frame the contributions of students, faculty and alums. Last night's stars were both from that last category.

The more conspicuous was soprano Harolyn Blackwell, a Washington native with a soaring, even and shining light soprano voice, and a buoyant stage personality. She charmed the audience with Mozart at his most delectable, the aria "Una donna a quindici anni" from "Cosi fan tutte," in which the cunning maid Despina lectures to her two mistresses on how to win at lovemaking. Irony and wit were sharply characterized and the sound was fresh and secure.

Then came Blackwell in Puccini's glorious "O mio babbino caro" from "Gianni Schicci," with shimmering sound and beautifully floated soft highs.

After that was the second act, the big party, from Strauss' "Die Fledermaus," with seven soloists and chorus. Strauss may be operetta, but it is tremendously challenging to the voice. After all, the great Rosalindas have not been light singers--but figures such as Lehmann and Schwarzkopf. You can't expect a music school to come up with voices of this weight very often--and last night's Nita Mensch Vorisek in this role was indeed outclassed.

One singer who showed real promise, though, was mezzo Ann Hart as the fopish, debauched Prince Orlorfsky. She had both the right sort of voice and the right sense of style. Near the end, especially, she was sailing right along. Further, she has a winning stage presence. A quite likable singer.

There also was a seldom-heard choral work, "Laudes Organi," with massive sonorities, especially from the organ, that were bigger than the work's ideas.

Two solo works with orchestra were performed. In the Grieg Piano Concerto, pianist Peter Simon made a huge sound in the bravura passages, but elsewhere there was roughness and he didn't do much with the concerto's lyricism.

In Tchaikovsky's Rococo variations cellist Ormand Bontempo, still an undergraduate, was agile and is worth watching in the future.