Kronos Quartet

Unless you've been paying close attention, the assumption that a 10-CD retrospective of the Kronos Quartet would contain their entire recorded output is understandable. Turns out you'd be very wrong: They've released some 30 recordings over the last 25 years, and, even more amazing, the world's most famous string quartet has performed a staggering 600 works in that time, many of them commissioned. Very few prominent classical composers over the last 20 years haven't written (or wanted to write) for this ensemble; Kronos' most formidable accomplishment may have been to make the ossified world of classical chamber music hip and marketable.

There is a lot of variety in these 10 hours of fiddle music. The most attractive pieces are those suffused with rhythmic energy, such as Kevin Volans' South African essays and John Adams' clever "Alleged Dances." The other "minimalists" — besides Adams — are well represented as well. The normally sleep-inducing Philip Glass has a lovely piece with richer harmonies than you might expect. One of Steve Reich's signature works, "Different Trains," is included, as is a colorful collection by Terry Riley, whose "In C" started the movement 30 years ago.

Kronos has obsessively cultivated pieces from cultures around the world, so the album contains intriguing specimens from Azerbaijan, aboriginal Australia, Vietnam and the like. Most listeners, no matter how open-minded, will find some tough nuts to crack here. Henryk Gorecki, the Polish composer whose second symphony was both a commercial blockbuster and a real snorefest, has two quartets that are unrelentingly grim. Another piece, by Russian composer Alfred Schnittke, is titled "Collected Songs Where Every Verse Is Filled with Grief." And Morton Feldman's one-movement "Piano and String Quartet" is 79:40 of slow piano arpeggios answered by inscrutable string chords, the soundtrack to a Zen experience most haven't been able to have yet.

No one is going to like it all, but that's one of the points of this group — to push the envelope and stretch listeners' ears at the same time.