Members of the National Symphony Orchestra presented a vibrant chamber music concert in the Kennedy Center's Terrace Theater on Sunday afternoon. The 15 musicians -- half of them assistant principal chairs -- collaborated on two 19th-century octets.

Felix Mendelssohn wrote his Octet in E-flat, Op. 20, in 1825, when he was 16. Scored for double string quartet, the octet marked a turning point in the young composer's career. In the hands of violinists Elisabeth Adkins, Holly Hamilton, Natasha Bogachek and Laurent Weibel; violists Lynne Edelson Levine and Nancy Thomas-Weller; and cellists Glenn Garlick and David Teie, it received a sprightly performance with dramatic volume drops and swells.

With a well-rehearsed musicality that was tempered by playful spontaneity, the musicians produced an especially adorable Scherzo. Zipping along and giving chase in the octet's fugue-like finale, the instrumentalists displayed the sort of teamwork conducive to winning a relay race. Melodic motifs passed from player to player with assurance and each musician took turns leading the pack. When all eight instrumentalists finally caught up to each another for the concluding unison melody, they expressed an infectious joy in their synchronized playing.

It took a 27-year-old Franz Schubert only two to three weeks to compose his hour-long Octet in F, D. 803, modeled after Beethoven's popular Septet in E-flat, Op. 20, written for winds and strings.

Clarinetist Eugene Mondie, hornist Laurel Bennert Ohlson and bassoonist Truman Harris produced brilliant layers of sound as sure and even as a pipe organ throughout the work. Violinists Ricardo Cyncynates and Jane Bowyer Stewart, violist Mahoko Eguchi, cellist Garlick and string bassist Richard Barber helped to create an especially warm and expressive Adagio movement and a capricious call-and-answer third movement.

In the finale, the string players' tremolos generated a bleak atmosphere before giving way to the cheerful main theme. However, during quick passages the strings had a tendency to play with a jagged timbre and seemed to rely on the winds to smooth out the overall sound. The winds were able to compensate for such tonal issues but couldn't mask the bouts of imprecise intonation in the upper strings that were surprisingly present throughout the octet.

The performance was part of the Kennedy Center's third annual Prelude Festival.