WILLIAMSTOWN — Two newly-minted chamber works, three living composers on hand to introduce their music, a searingly intense string trio by the Russian-German composer Alfred Schnittke and a curtain-raiser by Mozart based on Bach fugues. As presented Sunday afternoon at the Sterling and Francine Clark Art Institute by the Walden Chamber Players, what shaped up as a musical grab-bag turned out to be an eclectic and most rewarding venture into rarely heard repertoire.

Unlike some performing groups, the Waldenites, under the artistic leadership of resident violist Christof Huebner, go to great lengths to draw listeners into the music through extensive program notes in print and from the stage. Huebner, an unassuming, charming host whose remarks are brief and to the point, gracefully introduced the three guests.

Donald Wheelock is a longtime faculty member at Smith College and a prolific composer of large and small-scale works. Julia Scott Carey, an apparent child prodigy who started writing music when she was 5, graduated from the New England Conservatory of Music at 15 and is now a Harvard University sophomore.

The widely admired Berkshire-based Augusta Read Thomas, a Tanglewood Music Center alumna who recently completed a decade as composer-in-residence for the Chicago Symphony Orchestra and a teaching stint at Northwestern University, is now composing full-time.

Wheelock's Ten Bagatelles for Oboe and String Quartet, written in 1972, is an intriguing assemblage of miniatures — several of them last only 10 to 20 seconds. Precisely performed by oboe soloist Laura Ahlbeck, violinists Joel Pitchon, Anne Rabbat, violist Huebner and cellist Ashima Scripp, they lived up to the composer's own description — "mysterious but not forbidding or opaque."

Carey composed her String Trio for the Walden players. Speaking briefly, she citedhomas as her mentor and said she felt "privileged to be on the same program." The tantalizingly brief work (only four minutes) began with a wisp of melody followed by a burst of development, not enough to form a clear impression, though one had to agree with Huebner's post-performance remark that he wished there had been more.

Thomas, a longtime admirer of jazz, explained that she wrote "Scat" as an inversion of the stylistic technique in which jazz singers (Ella Fitzgerald, Louis Armstrong, Sarah Vaughan and Bobby McFerrin, among many others) imitate instruments either wordlessly or with random syllables and nonsense words. Her combination of oboe (or flute), violin, viola, cello and piano (or harpsichord) employs some gestures and elements typical of jazz, but comes across as a free-form, propulsive chamber work infused with tightly-coiled energy.

The Walden performers, joined by pianist Jonathan Bass, successfully captured the improvisatonal spirit of the eight-minute work. Thomas, who is spending most of her time composing at her Becket home and studio and will teach composition at the Tanglewood Music Center next summer, has created a fascinating piece that honors the jazz tradition while avoiding imitative "crossover" techniques. "Scat" is well worth additional hearings.

Bookending the American works was the opening performance of two of the six Bach fugues from the "Well-Tempered Clavier," arranged for string trio by Mozart, who added his own preludes. The sonority is strictly Mozartean, and the arrangements do full justice to Bach's contrapuntal genius. The performances by Pitchon, Huebner and Scripp were delicate and engaging.

Schnittke's two-movement String Trio, composed in 1985 just before his debilitating strokes, takes a solemn six-note theme and develops it into a fierce outcry of anguish. The theme resembles an upside-down "Happy Birthday" since the trio was commissioned to honor the 100th anniversary of Viennese composer Alban Berg's birth.

Using a combination of musical styles, Schnittke's protest against the Soviet regime's tyranny and destruction of artistic freedom concludes with the violin's prolonged, ghostly harmonic. Even more despairing than Shostakovich's chamber works, if that were possible, the trio is powerful and gripping, especially in such a committed performance.

The Walden Chamber Players are to be commended for their high performance standards and their adventurous programming. Regrettably, only about 50 highly-attentive listeners were on hand at The Clark, a sobering reminder that even in an enlightened college town, contemporary and unfamiliar repertoire is a tough sell.

Clarence Fanto