Dominick Argento's song cycle "Casa Guidi" provokes an adjective that can too seldom be applied to new pieces of music. It is beautiful. In its Washington premiere yesterday afternoon at the Kennedy Center, with Frederica Von Stade as soloist and Neville Marriner conducting the Minnesota Orchestra, its impact was overwhelming.

Composed in 1983, "Casa Guidi" represents another substantial step in the return of musical romanticism. The texts of its five songs are taken from letters of Elizabeth Barrett Browning, living in Florence, to her sister in London. With one exception, the texts radiate a quiet joy that is one of the hardest feelings to capture interestingly in music.

Argento does it extremely well, aided by a poet whose letters -- lively, perceptive, completely self-revealing -- may be even better reading than her poetry. The most striking, on a first hearing, is the second song, a comic discussion of the tensions between their Italian cook and their English maid -- with quotes from the cook, who considers it unnatural for any married couple to be as loving as the Brownings. The cycle opens with an ecstatic description of Florence, but at its heart lie her variously framed reflections on what it is like "for a woman to be loved by a man of imagination." The one exception to the prevailing mood of gentle joy is the fourth letter -- a poignant reflection on her father's death.

Argento has set these texts to an orchestral score of properly romantic lushness -- even recalling Richard Strauss in his descriptive crescendo for the line "the moon rises beautifully." The vocal line is free and flexible, sensitive at every moment to the words, eminently singable and tailored superbly to the rich voice of Von Stade. Texts were provided with the program -- fortunately, since the words were not always clear in this performance. Sometimes, they were simply swallowed by the acoustics of the Concert Hall; sometimes, the orchestra simply drowned out the singer. But the performance was effective and the applause was warm and prolonged.

The program opened with a fine performance of Bach's Magnificat, featuring the excellent St. Olaf Choir. Outstanding among the soloists were soprano Arleen Auge'r, tenor John Aler and bass Michael Devlin. Marriner also conducted a colorful, energetic performance of Respighi's "The Pines of Rome."