Riddle me this: What's been around for 22 years, lasts only 11 days, comes from all over the country but names itself after the Big Apple? No idea, you say? Wednesday night's Kennedy Center Concert Hall audience knows -- the New York String Orchestra.

Each year the best and brightest from the nation's conservatories are invited to audition for the privilege of studying in New York, playing two concerts at Carnegie Hall and one here in Washington. And each year Alexander Schneider, the founding inspiration behind this musical mayfly, seems to outdo himself. True, it might be the program (Wednesday night, a good dollop of Mozart and Wolf) or the artists. But one suspects the real secret to the New York String Orchestra's continued success is Schneider himself.

As a violinist with the fabled Budapest Quartet in the '30s, Schneider may be three times as old as this ensemble's youngest player, but his age belies the youthful spirit if not the maturity he brings to bear upon the music. Phrasing in Mozart's Symphony No. 25 in G Minor, K. 183, when it wasn't crafted with steely brilliance, was captured with a warm and pliant resonance -- a shade too brash in the closing Allegro, perhaps, but gloriously vital in the first.

Hugo Wolf's "Italian Serenade," though less tuneful than its Tchaikovsky and Dvorak string serenade cousins, is quite as lithe as either. The ensemble enlivened every note with a breezy exuberance even when the work's natural sunniness gave way to a stiff breeze.

Only Mozart's Concerto in C, K. 190, disappointed. Despite some rather lovely playing by oboist Charles Hamann, the whole failed to ignite. One shouldn't fault these fine musicians though. Mozart, one suspects, just had a bit of an off day.