The ensemble on this CD -- variously known as Accentus, Unicorn, and Oni Wytars -- is easily the most formidable medieval-renaissance instrumental ensemble in existence. I'm not just a rabid fan who's never listened to anybody else: I have methodically surveyed hundreds of early music CDs before arriving at this conclusion. If you haven't heard their name trumpeted by early music critics, it's probably because said critics are desiccated scholars instead of impassioned musicians (like most of the performers they critique). Accentus's main concern is the emotive capabilities of their instruments, and the four core members (Michael Posch, Marco Ambrosini, Riccardo Delfino, Thomas Wimmer; they're not listed in the notes for this release) are among the very few truly brilliant early music players. The heavy polyphony of Cabezon cramps their style a bit, but their phenomenal spirit shines through track after track. Many of their performance decisions on other albums are odd or less-than-historical; luckily for purists, though, "Tientos y Glosados" is straight and unmannered. It's the best of both worlds.