With the refreshing directness of youth, the New York String Orchestra gave a joyous concert at the Kennedy Center Concert Hall last night. One could feel the music breathing throughout the evening, and if at times it also panted awkwardly with the pace, the momentum on stage was never less than thrilling.

The ensemble, whose ages range from 15 to 22, was well served by its young soloists as well as director Alexander Schneider's fast but flexible conducting. It was two young violinists who stole the show, sharing the bill in concertos by Bach and Vivaldi. Krista Bennion, from the San Francisco Conservatory, and Ida Levin, from the Julliard School, showed some impeccable unison-playing in Vivaldi's Concerto in C, F. XII No. 14, where the orchestra played assertively and very idiomatically.

The young women were stunning in Bach's famous Concerto in D Minor for Two Violins, from the ominous ascending first theme through the patient charms of the Largo and the violent final movement. Bennion in particular showed a musicality beyond her years, with a fascinating blend of taste and impetuosity. She is a young artist to watch.

The featured soloists fared less well. Yefim Brofman and Stephanie Brown played Bach's Concerto in C Major for Two Pianos, S. 1061, falling for the pedal's temptations and blurring much of Bach's daring intricacy. But at least Brofman's energy gave the performance a thrilling flavor, and there was musical laughter in the phrasing of the strings.