The Toulouse Chamber Orchestra doesn't make a fetish of virtuosity or of brilliant tone. Among the ranks of small string ensembles (10 or 12 players) it falls rather on the warm and lush end of the scale.

Last night their Library of Congress program was divided between the Italian giants of the genre, Corelli, Albinoni and Vivaldi, and the music of two contemporary composers. One, Britten, is a giant in his own right, while the other, Jean Rivier, a composer of decidedly inferior stature.

The Italians for a change appeared in a gracefully flexible guise, with rounded corners and moments of gentle spaciousness. To ears accustomed to tighter, rhythmically mechanical performances of this music, it was a pleasant change.

Flutist Michael Debost made his first appearance of the evening in a square Vivaldi Concerto that was almost like a caricature of Vivaldi's music. If nothing else, it warmed him up and got the flute in tune. The second Vivaldi Concerto, much better music, was played sytlishly.

Rivier's Flute Concerto, written in 1957 in a kind of salon neo-modern style, was dull but harmless.

The concert ended with Britten's "Variations on a Theme by Frank Bridge," played with a devoted seriousness that missed some of the music's possibilities.