The New York City Opera closed its week at Wolf Trap with a smash hit in its gorgeous production of "The Student Prince." More than 16,000 people shouted their delight yesterday and Saturday at the three performances of the beautiful show.

Praise goes to all hands. First to conductor Brian Salesky for treating the fragrant, old-fashioned score with the spirit, affection and respect it deserves. Few musicals come up with anything as lovely as the Serenade, or "Deep in My Heart, Dear," "Just We Two," and all the rest.

Praise the designer David Jenkins and costumer Patton Campbell for catching so ideally the atmosphere of Sigmund Romberg's genius.

And praise the fact that Beverly Sills recognizes the value of having her company of excellent singers turn their talents to so wonderfully vocal a work in which the caliber of the singing is the finest in a long memory. ("The Student Prince" was the very first show of any kind that I ever saw in any theater.)

It doesn't matter that some of the book creaks or that there are lines that today provoke open laughter. When the Prince said, on Saturday night, "I don't know why I ever came to this place," some irreverent wit in the audience shouted. "I don't know either!" And a certain suspension of current vocabulary is required when the stunning men's chorus launches into one of the hit songs, "Come Boys, Let's All Be Gay, Boys."

This "Student Prince" is an almost unbroken succession of memorable songs put out by a remarkable cast. Jerry Hadley is an ideal prince, singing with ease and marvelous tone. cAnd he gets very special praise for the perfect beauty with which he sings the crucial word "dew," something few singers manage. Carol Gutknecht's Kathie has lots of appeal but she is prodigal with those very bright high C's, and she would do her voice a favor if she would use darker and quieter tones more of the time.

Praise Nadias Pelle's Margaret and Muriel Greenspon's Duchess, William Eichhorn as Tarnitz -- oh, just praise the whole crew. They are all wonderful.