There is no greater music for piano trio than the two major Beethoven and Schubert works performed by the Smithsonian Chamber Players last night in the Hall of Musical Instruments at the Museum of American History. Both trios have more profundity, variety and intense humanity than any one performance can encompass, but fortepianist Lambert Orkis, cellist Kenneth Slowik and violinist Marilyn McDonald, using old instruments and playing in the style of Beethoven's contemporaries, gave a fine idea of what the music offers.

Beethoven's "Archduke" Trio in B-flat -- the highlight of the first half of the concert -- still has a touch of strangeness 176 years after its composition, but its constant surprises are balanced and mitigated by its sense of inevitability. It is notable for its rough-hewn sense of humor, but even at his most playful -- in the bouncy second-movement scherzo -- Beethoven is never more than a step away from deep seriousness. The players caught this special emotional tone with precision in a bright, alert and deeply expressive performance.

Schubert's Trio in B-flat, D. 898, dates from the last year of his life and, under its shifting moods, has that special air of serenity that he managed to find in his final works while facing a horrible, premature death. The music's mood swings are less extreme than Beethoven's, and the performance was beautifully balanced and proportioned, carefully avoiding the kind of overstatement that would have been appropriate in the "Archduke."

Beethoven's witty variations on a popular song, "Ich bin der Schneider Kakadu," opened the concert. It is a slight piece, notable for the mock solemnity with which it introduces the insignificant little tune that is its subject. The performance was properly intense in the introduction and jaunty once the tune came on.