When violinist Henryk Szeryng comes to town he normally plays a big war horse like the Mendelssohn concerto. And when pianist Tamas Vasary arrives it's usually for one of the big-hitter concerto vehicles.

But at the Kennedy Center Saturday night they played chamber music with the Chamber Music Society of Lincoln Center. Instead of the glitter of Mendelssohn there wasthe intimacy of Mozart's B-flat major sonata in which the two collaborated for a flowing and subtle unfolding of the composer's ideas.

The whole concert was an exercise in improbability. There were two virtuosos getting together on a deceptively straightforward sonata that performers use not to display virtuosity, but musical sophistication. And there were Chamber Music Society staff virtuosos applying their skills to works almost never heard elsewhere.

Where else are you going to hear Barry Tuckwell, the most famous of horn players, perform the Andante e Polacca in E major by Czerny, the wrote all those scale exercises that have been the bread and butter of subsequent generations of piano students? Not a great work, but not a bad one.

Without the special circumstances that the Chamber Music Society affords, it would propably never have been heard. I, for one, was unaware of its existence, and I suspect the same was true for virtually everyone in Saturday's packed house. The performance, with Vasary at the piano, was spectacular.

For a spicy change of pace in the Janacek "Mladi" Sextet for winds, the Society's wind contingent, minus clari nets, was in full force. Once again the Lincoln Center players introduced an enormously attractive work that this listener had never even heard of, much less heard.

The Society polished off the evening with something familiar, the Brahms C major trio. The players were Vasary, Szeryng and the society's cellist, Leslie Parnas. The playing was expansive and refined.