The American Chamber Orchestra gave one of its free concerts Saturday afternoon at Anderson House. Amid the rather faded glories of that turn-of-the-century mansion, Mozart showed forth in splendor. The ensemble, made up of seasoned professionals, played well though with less than complete commitment under its conductor, William Yarborough. Tempos were brisk but rather rigid. Mozart should be allowed to sigh as well as to dance.

The program began with the String Divertimento, K. 136, and ended with the Symphony No. 10, K. 74. Sandwiched between these two well-crafted but cliche'-ridden works of Mozart's adolescence were two concertos that are among his most enchanting creations: the Horn Concerto, K. 417, and the Flute Concerto, K. 314.

Both soloists are first-chair players with the National Symphony Orchestra. Edwin Thayer's horn behaved beautifully, never once emitting an inadvertent burble. And it rode to the hounds with great panache in the rondo-finale.

The flutist, Toshiko Kohno, possesses a round, full, seamless tone. One only regretted that she chose to play an outdated, 19th-century style cadenza in the first movement of the Flute Concerto. Surely a fine musician like Kohno could have written her own brief and thematically relevant cadenza.