The Kronos Quartet has made its name by combining extreme virtuosity with equally extreme ecumenism of taste. The group brings the same seriousness to bear on Bo Diddley songs as on works by Arvo Part and George Crumb, so shock value has always been an integral part of their approach. But the Quartet's virtuosity is what saves that approach from gimmickry; they are almost always convincing in their implicit argument that you ought to take all of the music they perform as seriously as they do. This collection of pieces by minimalist Terry Riley consists of four works, all of which are worth hearing but none of which is especially inspiring. "Sunrise of the Planetary Dream Collector" takes a 14-note motif in the Dorian mode and turns it into a splayed, herky-jerky concatenation of lines that, when taken together, sound like the aural equivalent of tall, uncoordinated kids playing basketball. The piece is not without its charms, but it's not necessarily worth the investment of ten minutes of your life, either. More conventional and attractive are the jazz-based "G Song" and "Mythic Birds Waltz." The title track is a strange, 37-minute program piece thematically devoted to the most woolly-headed of received new age wisdom, from its explicitly India-derived structure to its piously anti-Western section headings. Again, it's not unpleasant, but it isn't compelling, either. Though Kronos plays with its usual incisive flair, the argument for serious listening is not terribly convincing this time out.