This week, the National Symphony Orchestra has two celebrity guest artists for the price of one--a familiar flutist and a conductor making his NSO debut, both named Jean-Pierre Rampal and both impressive.

Everyone knows how well Rampal plays the flute. The crucial question posed by this week's program was: Can he also conduct?

Tuesday night, in the Kennedy Center Concert Hall, the answer was an emphatic "yes." Rampal even managed to make a decent stab at doing both simultaneously in two concertos by Mozart and Cimarosa. The orchestra, in its first appearance since its Far East tour, was in excellent form.

The flute can produce more notes per second than practically any other instrument in classical music, and that may be one reason why Rampal's tempos Tuesday night tended to be perceptibly (never unreasonably) brisk. His baton style varies considerably from one moment to another, and occasionally seemed a bit unclear--at least from the audience. But his beat was certainly no less intelligible than that of many other fine conductors. There were one or two tentative-sounding phrases, but essentially the orchestra had no trouble at all.

Ensemble sound was, in fact, exceptionally precise in Rossini's "Semiramide" Overture, which opened the program. So were the balances and many fine nuances of phrasing--crescendos, diminuendos, staccato chords and solo obbligatos--the myriad small details that make Rossini so distinctive and so delightful.

But mere technique cannot explain the special joy that permeated the evening; it was the joy of old friends sharing a new experience. Rampal the flutist has long been a favorite guest at the NSO, which helped him to celebrate his 60th birthday last year in gala style. Rampal the conductor had an equally warm welcome Tuesday night, from the orchestra and the audience, and it was well-earned.

Beethoven's Second Symphony was the evening's most formidable assignment, combining large structural and stylistic challenges with a myriad of small, tricky details. Rampal has clearly done his homework carefully on this music.

He took the Adagio Molto introduction very slowly, giving the dotted rhythms (quite properly) some of the flavor of an 18th-century French overture, and building an effective contrast to his vigorous treatment of the exposition and development sections. Tuesday night, Rampal produced high-energy performances, though he avoided the spectacular podium calisthenics often associated with this kind of music-making.

His performance as a flutist was predictably excellent in Mozart's Concerto in D, K. 314 and Cimarosa's Concerto in C for two flutes, for which he was joined by NSO principal flutist Toshiko Kohno. To the surprise of no one who has observed her excellent work with the orchestra in recent years, Kohno proved to be a flutist completely worthy of sharing the spotlight with Rampal.