A gem of an orchestra from the Netherlands

The Concertgebouw Orchestra is not only the Netherlands' most prestigious cultural institution, it is one of the finest orchestras in the world - and has been for all of this century. Mahler was a regular conductor in Amsterdam. Richard Strauss dedicated ''Ein Heldenleben'' to former conductor Williem Mengelberg and the orchestra.

The group's quality has been more than evident from the countless records issued from the early days of recordings right through to the finest in today's digital technology.

But records are not always the best aural witnesses. The quest for excellence often means splicing and fooling around with buttons and dials to get that end. Happily, the Concertgebouw's formidable excellence is as amply audible in the concert hall - an excellence that even the finest, the most honest recording cannot fully capture.

To celebrate 200 friendly years of Dutch-American relations, a quantity of Dutch cultural talent has been sent across the United States this past year. The culmination has been, rightfully, the three-week coast-to-coast tour of the Concertgebouw.

The euphoria has been seriously tarnished, however, by the recent news that the Dutch government plans to economize by having music director Bernard Haitink drop 23 players from the roster. Mr. Haitink has responded by declaring that if the government goes through with this, he will resign his post and never again perform on a Dutch stage.

Maestro Haitink has been chief of the orchestra for 19 years, although he had made his conducting debut five years earlier. He continues a long tradition of excellence, from Mengelberg's nearly 50-year tenure through Eduard van Beinum, and the leadership he shared with Eugen Jochum.

Bernard Haitink continues to maintain the long and distinguished recording history. He has put to vinyl complete symphonic cycles of Mahler, Bruckner, and Brahms, most of the larger orchestral works of Debussy, and many of Ravel, all on the Philips label.

The recent release of a new Bruckner Eighth (6769 280 Digital - two records) is fully representative of Haitink at his best, as well as the orchestra at its most versatile and superb. The sound is first class. The performance fulfills what was promised on his first recording of the piece some 12 years ago. His insights have deepened, and he is now fully able to suffuse this visionary work with the requisite drama, to explore both the pinnacles of Brucknerian fervor and the depths of Brucknerian despair, and give the listener a true sense of journey. It is a vivid sampling of what makes the Concertgebouw

great, and what makes Haitink so special.

Hence, his threat to resign is at once disturbing and formidable - disturbing that such a severance is possible (and that a country with such a treasure could even think of tampering with it in any way); formidable in that a conductor could care so deeply he would give up what he clearly loves most in his musical life.

The recent Carnegie Hall concerts were the sort one expects to encounter only in festivals. The playing was of the highest order. The first desks are filled with virtuosos, who play superbly and with great individuality of tone. The orchestra favors a lean sound that ensures a transparency in dense textures without shirking enough of an edge to be heard distinctly at fullest volume. It is a sound at once individual yet versatile - ideal in Ravel, Keuris, Berlioz, and Mahler, yet always tangibly Concertgebouw.

With Haitink's exceptional sense of proportion, the score is a revelation, played for orchestral impact as well as for the more unusual, intimate chamber-music quality. Berlioz's ''Symphonie fantastique,'' for instance, has rarely sounded so rich in orchestral detail, and in the strength of the individual solo moments. Blends are evocative and superbly textured. The sound of the strings is not exactly sumptuous (though that quality is called up when needed), but they generate a glow that in the full moments gives an unusual thrill, yet in the quieter moments has a radiance. The brass is pliant and warm. The winds are unique in the orchestral world today - distinctive and characterful in solos, yet wonderfully blended in ensemble work.

The performance of the Mahler Seventh Symphony showed that Haitink's former approach to that work - committed to disk with his orchestra in the mid-'70s - has gained in subtlety (as with the re-recorded Bruckner) and in the ability to exploit orchestral color. So has his ability to sustain a unified, cohesive view of the work - one of Mahler's most complex to sort out. The mightiest peaks of Mahler's passions, however, are somewhat alien to Maestro Haitink's musical personality.

Clearly, the Concertgebouw is a Dutch treasure, and an international one as well. It can be heard (on Philips Records) in magnificent performances of Tchaikovsky's First (9500 777), Fourth (9500 622), and Sixth - ''Pathetique'' ( 9500 610). The Debussy disks are extraordinary, with ''La Mer'' (on 9500 359) and ''Nocturnes'' and ''Jeux'' (9500 674) being my particular favorites.

A recently re-recorded Bruckner Seventh, paired with Wagner's ''Siegfried Idyll'' (6769 028 - two records), is another example of fine interpretation wedded to orchestral playing of incomparable elegance and intensity - the trademarks of this equally splendid ensemble and director.