Heinz Wallberg came to Washington a few days early, not only to sleep off his jet lag but because he had never been here before. On Monday, before beginning rehearsals for his American debut, with the National Symphony Orchestra tonight, the 67-year-old German conductor could have been any tourist lunching at the Kennedy Center's Roof Terrace Restaurant and enjoying the panoramic view through its floor-to-ceiling windows.

"Is that the airport?" he asks, watching a plane come in for a landing at National and remembering his own landing at Dulles, "I thought it was much more distant... . What is that building {the Lincoln Memorial}? ... Can we see the museums from here? ... Does the National Symphony also play for the opera? Do I dress formally for rehearsals? ... With or without a necktie?"

His only previous visit to the United States, he explains, was in 1982, when he went to Los Angeles because one of his recordings (the first complete recording of Jiri Weinberger's opera "Schwanda the Bagpiper") had been nominated for a Grammy.

Wallberg, a native of West Germany and the general music director (opera and concerts) in Essen since 1975, has more than 100 recordings to his credit, including 17 of the 90-plus operas in his repertoire. He has been conducting in Vienna for the past 33 years and is a frequent guest conductor with the great orchestras, opera houses and festivals of Berlin, Munich, London, Leipzig, Salzburg, Leningrad, Rome, Budapest and Prague. Last month he had 13 concerts in Tokyo, where he has been a guest conductor for 19 years, and most recently he has been working at the Sydney Opera House and in Wellington, where his conducting of "Die Meistersinger" was hailed by a critic as "the most momentous night in the operatic history of New Zealand."

Why did it take Wallberg so long to make his debut in the United States -- or in France, where he will conduct for the first time next year? Looking at his schedule, you can appreciate the understatement when he says he has been "busy."

"I am here," he says, "because I was invited by a musician I respect enormously. Mstislav Rostropovich was my guest artist for the cello solo in 'Don Quixote,' and he told me, 'You must come and conduct my orchestra.' So here I am."

It might puncture American musical pride to think that a musician can have a distinguished international career and reach his late sixties without ever having performed in this country. But a clue to how this could happen pops up when Wallberg mentions his recording of "Hoffmanns Erzaehlungen." Most opera fans would translate the title mentally to "Tales of Hoffmann" or the original French, "Les Contes d'Hoffmann," but check out the EMI recording and the opening words of the chorus, "Aus dem Keller kommt hervor," ("Come forth from the cellar") make you realize why this set is available here only as an import. It is, in fact, "Hoffmanns Erzaehlungen," sung in German for a German audience. Since his debut in the late 1940s, Wallberg has been part of a busy and quite self-sufficient German musical culture, moving up the ranks from the music directorship of Augsburg to Bremen, Wiesbaden, the Vienna Tonkunstler Orchestra and finally Essen. Engagements outside of Germany have come more or less by chance, not as part of a career plan, and sometimes with a vacation-like atmosphere.

Wallberg has mixed feelings about the jet-set life of conductors who hold jobs simultaneously on two continents. "I can conduct a concert in Essen and be in Istanbul two hours later," he says. "I can go from Frankfurt to Tokyo nonstop in 12 hours. But I think there are dangers in that; you can get disoriented."

He has occasionally been disoriented himself, at least momentarily, with culture shock adding its impact to jet lag. One concert he remembers vividly was in Lisbon during the final days of the Salazar dictatorship. His description sounds like a movie by Bunuel.

"The concert was actually given in a circus," he says. "A military officer came to my dressing room with four soldiers bearing rifles; it was frightening. I wondered, maybe I had said something wrong? 'Do you speak Spanish, Portuguese or French?' the officer asked me. We settled on French, and it turned out he only wanted to invite me to have a glass of champagne with the prime minister and the diplomatic corps. He escorted me around the lions and elephants (they smelled very badly) and took me to an elegant reception where I saw a lot of hand-kissing but no love of music. Soon it became clear that the people at the reception had no intention of going to the concert. It was time to begin, and nobody was leaving. I told them, 'I must go now,' and they said, 'Not so fast, there's no hurry.' When I got back to the orchestra, they were worried. They told me, 'This is crazy, impossible; nobody knew where you were.' That night I conducted Beethoven's Fifth Symphony, tatata taaaa {his hands begin to wave an imaginary baton}, and later I was told it had never before sounded so fierce."

A modest conductor is a phenomenon almost as rare as a female baritone, but Wallberg seems to fit the description. His conversation is full of the fine musicians with whom he has performed, from Alfred Brendel to Dietrich Fischer-Dieskau and, most recently, Washington's own Alessandra Marc, who sang with him in New Zealand and with whom he is going to make a record. He talks about himself reluctantly, though he can be eloquent in a slightly abstract way on the work of a conductor.

Asked about the difference between opera and concert work, he says, "Opera is always an adventure" in a tone that makes you wonder how eager he is for adventure these days. "In opera," he says, "the conductor is there first of all to help the singer; he must know when to support the voice, but there are also times when the voice needs to be covered. The singer is up there, unprotected, without a score; anything can happen, and you must be ready to help in any way you can. When I am preparing an opera, I sing all the parts to myself, whether it is Constanze {a high soprano in "The Abduction From the Seraglio"} or Sarastro {a deep bass in "The Magic Flute"}. It helps a lot; you put yourself in the place of the singer; you know where the problems are, where it is necessary to take a breath."

In symphony concerts, more than in opera, he says, "You can give the music your signature; you can be alone on the stage with {composer Anton} Bruckner. In opera, the singer is the one onstage. But even in concerts, you must always be ready to consider more than one opinion; sometimes there is a soloist with whom you must reach agreement. And you can never make a simple decision and say, 'This is my tempo for this music, now and forever.' You must be ready to adapt to changing situations; you must recognize that the right tempo for one hall might be wrong for another."

After 45 years as a conductor, Wallberg says he is still learning. Some of the concerts he conducted in Tokyo were videotaped, and he is now studying the tapes. "It is so helpful to be able to see yourself and what you do," he says; "sometimes too much, sometimes not enough. It is a good opportunity to learn, and I believe it is important to learn something new every day. ... Every time you go out to conduct, you are taking a final examination."