Dmitri Shostakovich and Aaron Copland, famous as they are, have in common that much of their finest work--their chamber music--is less famous than their works that make bigger bangs. This could scarcely have been clearer than at last night's concert in the summer chamber music festival for young artists at the Library of Congress.

Shostakovich's G minor Quintet for string quartet and piano, which ended the program, is not even currently listed in the LP catalogue, but it is a major work, well worthy of mention in the same breath with the two masterpieces for this combination--the Schumann and Dvorak. It was written at about the same time as Shostakovich's most famous symphony, the Fifth, and bears all sorts of resemblances, especially in its sense of foreboding at the desolation about to sweep Russia. There is a stormy opening; the third movement is a giddy scherzo that tries to be a merry romp and instead turns manic and ominous. And just before the end of the last movement there is a chilling interlude high in the strings that is a first cousin of the Fifth Symphony's shattering largo.

The performance, by Mark Pesanov, Alexis Galperine, Miles Hoffman, Evelyn Elsing and Andre Laplante, was so well received that the scherzo was repeated as an encore.

Copland's Violin Sonata, played by Peskanov and pianist France de Guise, is less grand in scale but equally powerful in its way. In his chamber music (and his piano works), Copland goes out of his way to avoid the harmonic and melodic richness of the bigger pieces.

It is austere, terse, lean and understated. It may seem esoteric to some, but that is because Copland has reduced the music to the barest essentials to make his point. It is so pure that you are made as aware of what is being left unsaid as what is said. Peskanov phrased well, but did not begin to suggest the level of playing in other renderings, Isaac Stern's recording with the composer, for instance.

The evening opened with flutist Pamina Blum joining the players in the familiar Mozart D major Flute Quartet. Then she played beautifully Poulenc's elegant, witty and sentimental little Flute Sonata.