The notion somehow persists that chamber music is the exclusive property of a coterie. Susceptible to conspiracy theories, I wonder whether this fabrication has been stealthily spread by enthusiasts looking to keep demand down and prices low. Happily, the audience for Sunday evening's marvelous Sommerfest program of music for strings and piano by Prokofiev, Shostakovich and Fauré -- the first of only two chamber concerts in this year's festival -- was not deterred.

The common element in Sunday's admirable performances was Sommerfest artistic director Andrew Litton, who, amid a busy conducting career, evidently finds time to maintain his prowess at the keyboard. Emphatic when fitting, yet never calling undue attention to himself, Litton proved an exemplary ensemble pianist -- a species rarer than one might think.

First on Sunday's menu was Prokofiev's D-major Sonata for Violin and Piano -- a work for flute, arranged by the composer at the behest of the great David Oistrakh -- searingly enacted by visiting violinist Vadim Gluzman, who had wowed the crowd with Tchaikovsky's concerto the previous evening.

Like the Tchaikovsky, the sonata is studded with technical challenges; unlike the Tchaikovsky, its pleasures extend well beyond the pyrotechnic. From the romantic rubato of the Andantino to the signature spikiness of the finale, Gluzman and Litton had the measure of the piece; one could have guessed that they are frequent collaborators.

Litton's remaining co-conspirators were members of the Minnesota Orchestra's string section, all quite ready for their close-ups. Concluding the program was Gabriel Fauré's Piano Quintet No. 2, one of the French master's twilight utterances: a work spare yet ardent, sober yet languorous. Violinists Gina DiBello and Milana Elise Reiche, violist Kenneth Freed and cellist Eugena Chang endowed their sound with a Gallic sheen; DiBello's songful, 24-bar line in the second movement was ravishing.

Best, to my ear, was Dmitri Shostakovich's 1934 Cello Sonata, played -- or better, inhabited -- by principal cellist Anthony Ross. This is music of huge scope and depth, and the mingled intensity and restraint of the performance gave it its due. The delicate nostalgia of the opening, the clumsy folk dance of the second movement, the engulfing gloom of the Largo, the dripping sarcasm of the Allegretto -- everything was there, unforgettably.

Larry Fuchsberg writes regularly about music.