The Coolidge Auditorium at the Library of Congress has been the site of more distinguished chamber music premieres than any other spot in the country. Last night there was another -- George Rochberg's appealing new Quartet for Piano and Strings.

It is a post-serial, one movement work about 25 minutes long that is of considerable dramatic intensity. These days the composer, whose music was once arcane indeed, makes a point of being communicative. There is a fresh and imaginative range of sonorities, often at remote parts of the instruments' ranges.

Structurally, the work is direct, but unconventional. It begins, ends and is held together by slow, misty passages that are played softly and barely seem to move at all -- a little like some of Barto'k's haunting "night music" but less harrowing in effect. They are harmonically ambivalent and consist not so much of melody as of fragments that suggest melody. This material serves as a connective for a wide variety of episodes -- most of them brief and aggressive. There is one particularly bold one, for instance, in which the instruments -- sometimes together and sometimes separately -- leap all over their ranges in octaves.

This is virtuoso stuff, and the new work received a virtuoso performance, obviously very carefully prepared by pianist Christopher O'Riley, violinist Alexis Galpe'rine, violist Miles Hoffman and cellist Peter Wiley. Rochberg was present and was enthusiastically applauded.

It was an evening of piano quartets. The same players performed a polished, deftly detailed version of one of the greatest ones, Mozart's piano quartet in E-flat, K. 493. This quartet is not psychologically deep in the sense of the G-minor string quintet, for instance. It is merely perfect. One might describe it as play, but it is sublime play. O'Riley was especially fine.

There was also Brahms' stirring barn-burner of a work, his Op. 26 quartet, in A-major. The piano part is as difficult as a concerto. It was played last night by Hugh Wolff -- the same Hugh Wolff who is the National Symphony's associate conductor, the new music director of the New Jersey Symphony and the recent recipient of the $75,000 Seaver grant. His performance was not terribly subtle, but he swept Brahms along with that same unerring rhythmic sense that he always shows on the podium.