Frederic Rzewski. (Michael Wilson)

One segment of musical Washington not on hand at the Kennedy Center for opening night of the “Ring” Saturday night could be found at Coolidge Auditorium at the Library of Congress for an intriguing concert that included a world premiere by Frederic Rzewski and a local premiere of the Tenth String Quartet by Ben Johnston. The evening incidentally honored Rzewski’s 78th birthday in April and Johnston’s 90th in March.

Rzewski took the stage for the first half, playing two recent solo works, “Winter Nights” and “Flowers.” It’s hardly surprising that the composer of one of the peaks of American piano music, the “Variations on ‘The People United Shall Never Be Defeated,’ ” is himself a formidable pianist. Rzewski commands an arsenal of expressive attacks and releases that would make most concert pianists green with envy. He also can produce the loudest sound I’ve ever heard from the instrument, one that is achieved seemingly effortlessly, without harshness or brutality.

The quiet conjuration of darkness and cold in “Winter Nights” drew the audience in immediately. “Flowers” requires the pianist to speak as well as play, in this case a text from Dickens’s “Little Dorrit,” music and text interweaving in a poignant portrait of loss.

Violinist Jennifer Koh joined Rzewski for “Satires,” the thorny five-movement dialogue between violin and piano newly commissioned by the Library of Congress. Koh and Rzewski were equal partners in a virtuosic display of hand-in-glove ensemble playing of this challenging and multi-layered score.

After intermission, the Del Sol Quartet, the energetic and persuasive young ensemble from San Francisco, took the helm. The first String Quartet of George Anthiel, one of the bad boys of the American avant-garde during the 1920s, may have been the least interesting offering of the evening, with its ostentatiously insistent dissonance and overall lack of rhythmic variety. Despite a committed performance, in the context of so much new music it sounded dated.

Del Sol Quartet. (Matthew Washburn)

Johnston’s Tenth String Quartet, on the other hand, proved a stimulating finale at the end of an already long evening of intense listening. Johnston employs “just intonation,” a tuning system different from the “equal temperament” that we’re accustomed to today. Adjusting our ears to this different tonal orientation had a refreshing effect, abetted by the rhythmic vitality Del Sol brought to their performance. Each of the four movements prompted applause, especially the last. After an ambiguous modal beginning, it evolved into a series of variations on the Irish traditional tune best known as “O Danny Boy.”