by Jason AnkenyFew groups have so successfully bridged the gap between classical and popular music as the Kronos Quartet; expanding the parameters of their repertoire to include compositions from rock, jazz, and world music, the New York-based artists have recorded a body of work virtually unparalleled in its dedication to innovation and range of expression. Originally comprised of David Harrington on first violin, John Sherba on second violin, Hank Dutt on viola, and Joan Jeanrenaud on cello, the Kronos Quartet was formed in San Francisco in 1973; though all four members were classically trained, they quickly dispensed with the rigid formalities of their craft, performing their chamber music with all of the impassioned energy commonly associated with rock -- even their casual dress flew in the face of the classical establishment. Although Kronos began recording during the late '70s, they began attracting widespread notice during the middle of the following decade as a result of recordings like 1984's Monk Suite (a collection of classical performances of compositions by Thelonious Monk and Duke Ellington) and their 1986 eponymous Nonesuch label debut, which raised many eyebrows via its string quartet cover of Jimi Hendrix's "Purple Haze." In the years to follow, the uniquely eclectic and unpredictable quartet remained several steps ahead of its contemporaries at all times, commissioning pieces from modern composers like Philip Glass, Terry Riley, Steve Reich, and John Zorn; performing the works of tango innovator Astor Piazzolla and free jazz visionary Ornette Coleman; and exploring world music (1992's Pieces of Africa exclusively featured music native to the African continent). Joan Jeanrenaud left the Kronos Quartet in 1999 and was replaced by cellist Jennifer Culp. Culp subsequently departed following the recording of 2005's You've Stolen My Heart: Songs from R.D. Burman's Bollywood; the group announced in August of that year that Culp was being replaced by Jeffrey Zeigler, who had occasionally appeared with Kronos as a guest cellist.