Bill Frisell is a master in all settings, both conventional and improbable; in some of his best recorded work, he's not the leader but a sideman adding his voice to the mix. He stands out by fitting in. The only thing I haven't heard is solo guitar: he wants others around him, and the result is collective improvisation -- not a string of solos but ensemble playing, relaxed and spontaneous. The 858 Quartet is, as other reviewers have noted, a string quartet with the guitar as the central or leading voice, but in these pieces, Frisell's voice is often unobtrusive. The four are a very tight unit; their playing is intricate, within the constraints of rather simple motifs; you can hear the pleasure they take in listening intently, responding to and supporting each other. It's music that richly repays repeated listenings. Some pieces may make you want to dance: I'd love to see what a group of professional dancers would make of the material, with or without a choreographer.