Ronald Reagan went to see "La Bohe me" Saturday night at the Kennedy Center, and the earth stood still -- at least for several blocks. The opera crowd was fairly well in place before the president arrived, but the audience for the Concert Hall (where the Chamber Music Society of Lincoln Center was scheduled to start a half-hour after the opera) found roadblocks at the Kennedy Center and traffic jams on all sides.

At starting time for the chamber music concert, the hall was still barely half full while ticket holders scrambled for parking spaces as far away as the State Department, and a whole floor of the Kennedy Center parking lot, cut off by a police cordon, remained empty. The concert was delayed, but still some people missed part of the music. Fortunately, the concert was worth all the trouble and the performers had scheduled the best parts for the end.

One highlight was Ravel's Introduction and Allegro, a masterpiece of beguiling melodies, intricate interactions and exquisite textures that has been known to sound almost like a harp concerto in some performances. This time it was beautifully balanced with guest harpist Osian Ellis acting as a first among equals. And the members of the Lincoln Center group were in fact his equals, despite the harpist's formidable reputation. On a stage occupied simultaneously by Ellis, clarinetist Gervase de Peyer, flutist Paula Robison, violinist James Buswell, violist Walter Trampler and cellist Leslie Parnas, individual and collective greatness can be taken for granted.

Buswell had the spotlight in Saint-Sae ns' Fantasie, Op. 124, for violin and harp, a sequence of melodies (mostly for the violin) that raises salon music to the level of high art. In Debussy's Sonata for Flute, Viola and Harp, Robison and Trampler demonstrated how the flute and viola can engage in a dialogue so close and precise that one voice merges seamlessly into the other.

The Haydn Trio in G that opened the evening is a brief, rather eccentric work, paradoxical in the feeling it gives that the movements are played in the wrong order, but also beautiful -- particularly in the melodious opening adagio. The middle movement was played at a lightning pace that seemed chosen simply to show that the players could do it.

Those who have called Andre'-Michel Schub a cool, cerebral pianist obviously have not heard him in the Brahms G-minor piano quartet that closed this program. His was most often the dominant voice (though never overbearing) in this impassioned music, which he brought to searing heights of intensity in the climactic third movement before dissolving its seriousness into laughter and dancing in the gypsy melodies of the finale. Since winning the Van Cliburn competition, Schub is probably headed for a career primarily as a solo virtuoso playing the big concertos, but if he leaves chamber music entirely it will be a serious loss.