The King's Singers, a English a cappella sextet with a long history of iconoclasm, exceed even their own previous exploits with this recording of Thomas Tallis' 40-part motet "Spem in alium." This is a CD single, including the Tallis work and an interview with the singers in which they discuss not only the obvious questions that arise -- how did they sing 40-part music with six voices? -- but also some less obvious ones: wouldn't it have been easier if Tallis' work had had 42 voices? (Tallis' 40 parts are divided into eight choirs of five.) The answer to the first question is simple for any pop listener but represents a new thing in the classical world: they use multitracking. How does it work? "Spem in alium" sounds completely different here from the usual effect it makes with 40 singers, or some multiple of 40, holding forth in a cathedral. The points where these tectonic plates of sound grind against each other come into much sharper relief in this close-up studio setting, and the palette of dissonances that Tallis must have heard in his head is suddenly revealed. The polyphonic structure of the work in general is clarified immeasurably; in ordinary performances, the ear must be carefully focused to pick out details from the large mass of sound. On the other hand, a perhaps less desirable effect is that the text enunciations of the individual voices are heard more clearly here as well. Text consonants that get lost in a larger space here are heard as a constant chatter, rather like background conversation at a crowded party. It's worth noting that "Spem in alium" was a freakish piece to begin with, a sort of game of one-upsmanship being played by Tallis and an Italian composer who wrote a similar piece. One likes to think that Tallis would have approved of further experimentation with it. At any rate, the King's Singers make it clear in the interview that they don't think of this as a definitive "Spem in alium." It is however, an intriguing sound extravaganza built on a piece that was a sound extravaganza in the first place. The sound is gorgeous on an ordinary stereo, and owners of such can only dream of the splendors that await those able to reproduce the SACD surround sound on the disc.