The members of the audience at last night's Library of Congress Summer Chamber Festival concert were in a festive mood. Clearly they were enjoying the temporary reopening of the Coolidge Auditorium, a hall that has been a central part of the musical life of this city for so long and has been closed for a year for renovations. They were also celebrating the friendly and collegial music-making of the group of fine artists who have been bringing their early summer series to the library since 1982.

The piece that seemed to match the spirit of the evening most closely was the delightful "Duetto" for cello and double bass by Rossini, a three-movement romp for coloratura bass instruments. Cellist Julia Lichten and bassist Frank Carnovale negotiated the highly ornamental lines with evident enjoyment and astonishing virtuosity and weightlessness.

The evening began with a somewhat nervously paced performance of the Mozart "Eine kleine Nachtmusik," made orchestral in sonority by the addition of the bass doubling the cello. Pianist Ann Schein and violinist Alexis Galperine gave a carefully detailed reading of Rochberg's attractive but occasionally labored Sonata, and the concert ended with a brisk performance of the Beethoven D Major Trio, Op. 70, No. 1.