The Theater Chamber Players is among the burgeoning collection of ensembles for which the art of programming has become almost as important as the mode of performance. Blessed with a large pool of excellent performers to draw upon, its available repertoire is vast, much bigger than that available to the traditional string quartet.

That this opulence presents pitfalls as well as felicities, however, was evident in the concert that opened the Library of Congress season last night.

For the most part, each of the five pieces played was, individually, delightful. The exception was Harrison Birtwistle's "Monody for Corpus Christi," scored for soprano, flute, violin and horn. It is an abstract concoction that manages to make its romantically metaphysical text sound superfluous.

But so diverse was the selection -- two Morley canzonets, the Birtwistle, followed by the Hindemith Clarinet Quintet and, after intermission, Briten's Canticle III and the Prokofiev F Minor Violin Sonata -- that each piece eradicated the mood and sound of its predecessors instead of providing a congenial context for them.

Soprano Phyllis Bryn-Julson, as usual, sang magnificently in the Birtwistle. Tenor James McDonald was adequate if less than inspired in the Britten, and the rest of the ensemble performed with the excellence one has come to expect from the Theater Chamber Players.