In a music world where young lions get fat and lazy once their appetite for acceptance has been sated, it's good to know that some musicians stay lean and hungry for the shock of the new long after their financial gut is full. Such is the case of the Kronos Quartet, the group that for a quarter-century has expanded classical music's edge--and its audience in the process.

"I've always wanted the string quartet to be vital, energetic, cool and not afraid to kick ass," says group founder and first violinist David Harrington, in the kind of grooving-on-a-riff banter usually reserved for jazz musicians. "It has to be absolutely beautiful and ugly and expressive of life and willing to tell the story with grace, humor and depth."

From its early settings of Thelonious Monk's bop anthems for string quartet to the international border crossing of their latest recording, Caravan, the quartet--consisting of Harrington, violinist John Sherba, violist Hank Dutt and cellists Joan Jeanrenaud and, now, Jennifer Culp--has acted as a vessel for a new repertoire. In its 27 years, Kronos has commissioned almost 500 new compositions and arrangements by the best and the brightest of classical music's new wave. This refilling of the reservoir has been the group's raison d'être since Harrington first heard George Crumb's frantic hymn to the Vietnam War, 1970's Black Angels. The work's jolting sense of current-events urgency flew in the face of staid chamber-music convention and acted as catalyst for the then-young Portland-born musician. A year later, he started Kronos.

The group has since solicited work from New Music's pantheon--Philip Glass, John Adams, Steve Reich and Terry Riley. Kronos has also mixed with contemporary European masters like Alfred Schnittke, Henryk Górecki, Arvo Pärt and Witold Lutoslawski. With Caravan, they take on the world through a dozen works by a delegation of international composers unknown to most Western ears.

The disc is not Kronos' first foray into internationalia. They've worked with Argentine nuevo tango godfather Astor Piazzolla and South African composer Kevin Volans and created 1992's acclaimed Pieces of Africa, a wall-cracking marriage of string quartet and African percussion.

But it's the group's late-'70s work with composer and international musicologist Riley that Harrington cites as "hugely influential."

"We had to adopt a rehearsal method with Terry's work," says Harrington, "making major compositional decisions in how the notes are shaped, shaded and colored. He'd provide the pitches and rhythms, but the dynamics and direction were left to us. We found a completely different way of approaching our sound."

Such egalitarian openness proved an awakening for the four young musicians. In setting aside the accepted norm of first violin-second violin call and response with viola underlining and cello bass, they rewrote the rules of classical music. It's this unorthodoxy that makes Caravan such a treat. Even in an age when post-modern sensibility dictates amalgamation, Caravan is a refreshing hybrid.

Opening with Pannonia Boundless, an eerie piece of pulsing ambience by 30-year-old Yugoslavian composer Aleksandra Vrebalov, the disc tours Latin America, the Middle East, and even India's Bollywood. Argentine-Israeli Osvaldo Golijov arranged eight of the works for string quartet, and each crackles with the freshness of its harmonic parrying. Fittingly, Terry Riley is back aboard with the second movement of Requiem for Adam, an electro-acoustic Dies Irae to Harrington's son Adam, who died at age 16. (The full 42-minute work will be played at Reed.)

"Caravan's an attempt to change the palette," says Harrington. "It was inspired by a Czech gypsy string orchestra I heard. The kinds of tones they managed were so very, very sad and yet very joyful at the same time. It impressed upon me how one note can travel the expanse of human feeling."

Despite its skin-deep comparison to Pieces of Africa, Harrington sees Caravan as part two of a trilogy of works that began with 1997's rumination on medieval and Renaissance influences, Early Music, and will end with a new recording. "The trilogy's about the way we think about musical time," says Harrington, "and how confusing it is when a composer who lived in the ninth century sounds like they wrote music that's urgently contemporary." Part three will continue on this inner emotional quest, peeling back the layers of music and its semantic tools of rhythm, melody, harmony to reveal the emotional core. Harrington elaborates: "It'll be about reconciling the unbridled joyfulness and the underlying sorrow always there--and not forgetting the journey we've traveled."

"The color will be very bright and bold," says Harrington, imagining what's not yet there. Can he elaborate? He gets worked up to riff on his ideas but suddenly settles down on the other end of the phone. "I'd rather surprise you."