The Juilliard Quartet gave violist Samuel Rhodes the evening off last night in a concert at the Library of Congress that paired its remaining members in various other chamber music combinations with two eminent guests, clarinetist Stanley Drucker and pianist Jens Nygaard.

It was, above all, a night for trios -- clarinet trios, to be specific.

One was the youthful B-flat major Trio (Op. 11) of Beethoven, a work he wrote in 1798 that combines 18th-century artifices with a 19th-century sense of adventure. It is for clarinet, cello and piano.

The other isn't called a trio, but it is. It is Barto'k's "Contrasts," composed in 1938 for clarinet, violin and piano.

"Contrasts" is a trio of great power, written when the composer was at his peak on a commission from Benny Goodman and violinist Joseph Szigeti. It is full of the eerie timbres, modal harmonies, motor rhythms and anxious intensity that typify late Barto'k.

If Barto'k didn't call it a trio, that is for two reasons. One is that the movements are not as rigorously developed structurally as his six quartets. And the other is that he didn't set out to write a trio; he was going to write a two-movement rhapsody. But when that was done with two movements, he decided the work needed a brief, contemplative movement to separate them. And with that, the work assumed the three-movement proportions of the classic trio -- and it is one of the finest trios of any kind written in this century.

The performance had immense force. Drucker, the first chair clarinetist of the New York Philharmonic, plays the instrument as well as anybody. Rhythm was immaculate. The same was true of Earl Carlyss' playing of the violin part. Nygaard handled the percussive (in the most sophisticated sense of the word) piano part with the same poise and musicality he showed all evening.

The Beethoven was not so worldly a creation. But it is full of exuberance and was played with tremendous dash by Drucker, Nygaard and cellist Joel Krosnick.

Carlyss and the quartet's first violinist, Robert Mann, played 14 of Barto'k's little Duos for two violins, most about a minute long and based on Slavic folk themes.

Mann and Nygaard also gave an urgent, passionate account of Mozart's C-Major Violin Sonata, (K. 296).