From St. Hedwig's Cathedral of Berlin came an expert choir and orchestra to sing, in the Kennedy Center yesterday afternoon, the C Minor Mass of Mozart and the Bacn "Magnificat."

With two such masterworks, any adequate performance makes a memorable occasion. The Berlin musicians, under the solid direction of the Cathedral's choirmaster, Roland Bader, gave far more than that. Their style was crisp and clean, always on the side of a lighter, brighter sound rather than one with any undue weight. A superb musician gave the finest support at the organ.

Bader wisely limited the Mozart to those passages the composer finished, in this, one of music's most glorious incompleted works. Despite the program's printed matter, the Bach was sung without the chorales which can, but need not be, interpolated.

With outstanding orchestral soloists, especially the flute, oboe and bassoon in "Et incarnatus est," and brilliant trumpets in the Bach, the instrumental side of things was in top shape.

The vocal soloists also stood up well; only the bass was out of class in the "Magnificant." Many of the day's greatest splendor came in the singing of Arleen Auger, radiant in tone in "Et incarnatus est." Such effortless singing has rarely come along in years.

Auger is an American now making her career in Germany. We need her desperately in this country. She was hamdsomely seconded by soprano Christiane Hampe and mazzo Barbara Egel, with tenor Josef Becker singing sensitively in the Bach.