It's hard to remember a time before the Kronos Quartet. Founded in 1973, the ensemble -- violinists David Harrington and John Sherba, violist Hank Dutt and cellist Jeffrey Zeigler, who, having joined in 2005, is the baby of the group -- has birthed more than 700 pieces and a shelf of CDs. It has survived Morton Feldman's six-hour Second String Quartet (for which the players trained like Olympic athletes) and the administration of Gerald Ford. Along the way, it has shown irrefutably that "hip string quartet" is no oxymoron.

Kronos' Friday evening concert, the first of two contrasting programs at the Walker Art Center, highlighted a central strand of the quartet's activity: its mining of the music of peoples and cultures under stress -- music seemingly more urgent and more pointedly communicative than that conceived under conditions of relative security and comfort.

Drawn largely from the 2009 album "Floodplain," the program offered a characteristic mix of commissioned pieces (the best of them by women from Azerbaijan and Serbia) and arrangements of traditional and vernacular music, together with a somewhat disappointing excerpt from "Salome Dances for Peace" by American minimalist master Terry Riley (who at times has looked like Kronos' house composer).

Those disposed to sniff out colonialist impulses will easily find them here. Kronos' (or rather Harrington's) restless global gathering and reframing of musical specimens can be seen as appropriation, or cultural tourism, or both. Its motives are open to question.

Yet to me, it's not so different from what Béla Bartok was doing with Hungarian folk songs a century ago. It promotes the circulation of potent sounds that might otherwise never leave home, and does it with a digital wrinkle unavailable to Bartok: Almost every arrangement includes a taped component that supplies context and counterpoint. This can feel intrusive, especially when the recorded sounds vie with the live quartet for the musical foreground. But the best tapes create a reflective space around the musicians, inviting a dialogue that enriches the performance.

Kronos has been in the game a long time, and some of its rhetoric has paled. In 2011, one grows a little weary of the boundary-defying and genre-bending, the envelope-pushing and medium-reinventing -- as one does of the self-conscious coolness that has always marked the group. But Kronos has been, and remains, a lively force for musical good, influential out of all proportion to its size. Long may it play!

Larry Fuchsberg writes about music.