Before the music began, it looked like the chief value in last night's chamber music concert at the Library of Congress would be found in the unusual programming: the 1953 Sonata for Horn and Piano by Halsey Stevens; the Three Songs, Op. 45, of Samuel Barber; the song "Auf dem Strom" by Schubert, which is relatively seldom heard because it adds a challenging horn part to the standard voice-and-piano format, and even Beethoven's slight but charming Serenade in D for flute, violin and viola. None of this music is heard as often as it deserves.

But all these rare delicacies were clearly surpassed by the least enterprising item on the program: Robert Schumann's tired old Quartet in E-flat for piano and strings. Old the music undeniably is--140 years old to be precise--but it was anything but tired last night in the hands of pianist William Black, violinist Junko Ohtsu, violist Matthias Buchholz and cellist Evelyn Elsing.

The melodies, which are its clearest attraction, were beautifully shaped, but what really made it work was the sense of interaction, at a level that one expects from ensembles seasoned through years of working together. The four young players, who came together only a few weeks ago for the Library's chamber music festival, were precisely balanced, alert and crisp in their rhythms and carefully controlled in the way they built tension to climactic points. Above all, they played as sharers of a common vision, and the contrasting moods and structures of the work's four movements were beautifully defined.

In contrast, the Beethoven Serenade never happened. Instead, violinist Alexis Galperine, violist Miles Hoffman and cellist Carter Bray played a Schubert movement for string trio that began tentatively and was almost over by the time the players were really working together. Soprano Barbara Shuttleworth sang the Barber and Schubert songs with fine style but occasional problems of pitch and timbre. The Barber songs were more interesting for the well-chosen texts than for the music.

Anthony Cecere was frequently brilliant and sometimes eloquent on the French horn, both in the Schubert song and the superbly constructed Stevens Sonata, despite occasional small lapses of intonation and occasionally more volume than is really comfortable in the Coolidge Auditorium.