The up-and-coming Dover Quartet brought unfamiliar and rewarding work to the Library of Congress. (Carlin Ma/Carlin Ma)

Even discriminating listeners may not actually be able to tell the difference between a Stradivarius and a newly made violin. That, at least, was the finding of a blind test run a couple of years ago. But classical music lovers cite that test with scorn. The mystique of the Stradivarius prevails: The idea of the finest stringed instruments in the world, preserved through centuries and endowed with ineffable, intangible, inimitable qualities, lines right up with the prevalent myths about classical music itself.

Certainly the Library of Congress's Stradivarii sounded pretty wonderful Monday night, when the Dover Quartet took them on their annual airing — the 80th time the library has marked the anniversary of Antonio Stradivari's death, on Dec. 18, with a performance on some of the library's collection of his instruments.

The Dover players, touted as emerging stars, presented music written during the turbulent passage between Late Romanticism and modernity, showing the last stands of the canonical Romantic-era tradition just before it was refracted through the prism of the 20th century: an arresting trio of unfamiliar works. The most recent was presented first: the third string quartet by Viktor Ullmann, one of the few works by that composer to survive, written in the concentration camp at Theresienstadt not long before Ullmann was gassed at Auschwitz. Ullmann's dramatic and tragic history sometimes overshadows the quality of his work, which appears frequently on programs focusing on composers suppressed by the Nazis. This quartet, the only one he wrote that survives, is a fluid, beautifully crafted and intelligent ride, with a soft gentle center and a vivid Rondo-Finale at the close.

Arnold Schoenberg was the next name on the program, but this was a Schoenberg so young he could be mistaken for Brahms's little brother, or a cousin of Dvorak. This D major quartet, written when he was 23, starts with a lusty opening that sounded more like "Turkey in the Straw" than the rigors of 12-tone serialism that the composer developed later. Indeed, according to remarks by the quartet's violist, Milena Pajaro-van de Stadt, Schoenberg's teacher, Alexander Zemlinsky, took some of the sketches for the piece to Brahms himself, who reacted with enthusiasm (as did the audience).

The capstone of the concert was the second quartet by Zemlinsky himself, beautiful and epic and intricate and dedicated to the student, Schoenberg, whose fame was ultimately to eclipse the teacher's. The piece was written during World War I, the first of the century's great anguished convulsions, and makes audible the intensity of the transition between the treasured ideas of the 19th century and the intellectual rigors of the 20th.

The quartet, intelligent and distinctive players all, brought poetry on the unfamiliar instruments. Whether one can truly hear the difference in a blind test, the Strads shared a common timbre Monday: a warm rich sound with a hint of otherworldliness, an almost inhuman, nearly electronic quality, like a very old wine, or a voice raised, for a moment, from the grave, in a program that not only repeated the past but illuminated it.