In youth-orchestra programming, hard experience has taught, discretion is the prime virtue. Samuel Wong's valiant program for the first concert of his second season as music director of the New York Youth Symphony on Sunday afternoon at Carnegie Hall seemed, therefore, to carry the likelihood of failure and the potential for disaster. In particular, it was hard to imagine that the youngsters' attempt at Stravinsky's ''Rite of Spring,'' looming after the intermission, could amount to more than a talking-dog affair - a marvel if they were able to negotiate it at all.
They did more than negotiate it; they played it very well indeed. And just as surprising, this was no more than one expected after hearing the fine performances of scarcely less difficult material before the intermission: Wagner's Prelude to ''Die Meistersinger,'' Robert Maggio's ''Dorian Prelude'' and Ravel's ''Ma Mere l'Oye'' Suite. Despite inevitable difficulties throughout the afternoon, mostly trivial, there was never anything blatantly inept or studentish in the overall impression. The massed sonority in the Wagner was especially robust, and the solo playing of the concertmaster, Hye-Kyung Seo, was remarkably refined, even in Ravel's tricky harmonics.
Other individual string players came to the fore in the premiere performance of Mr. Maggio's work, which the Youth Symphony commissioned as part of its First Music series. The 25-year-old composer, taking inspiration from Oscar Wilde's ''Picture of Dorian Gray,'' has produced an imaginative and vibrant concert overture. Its orchestration, which proved striking even in the rich context of this program, gives way on three occasions to passages featuring four solo strings -violins, then violas and finally cellos.
That the viola soloists were notably weaker than their counterparts reflects the unconventional distribution of the orchestra. The Youth Symphony consists of more than 100 players between the ages of 12 and 22, not necessarily bent on musical careers. In a string section of 60, for reasons undoubtedly tied to the quantity and quality of available candidates, a mere 8 violas are left to compete with 33 violins and 15 cellos (the latter compensating in part for another shortage: only 4 double basses). Ideal orchestral balance has been sacrificed, presumably to accommodate as many excellent players as possible. On this occasion the decision was vindicated by the results, which would have done any conservatory proud.