The male vocal quartet, the Orlando Consort, and the Estonian Philharmonic Chamber Choir share a commitment to the same repertoires — the very old and the very new. The earliest and latest pieces on this collaborative CD are separated by about 650 years, Guillaume de Machaut’s Messe de Notre Dame, probably written in the 1360s, and works by the British composers Gavin Bryars and Tarik O’Regan in the twenty-first century. The programs notes include a wonderful story from the 1930s, in which an audience member told the conductor after a performance of the Machaut Mass, “We don’t want to hear dodecaphonic music, we want to hear old music.” For ears accustomed only to music as early as the Baroque, Machaut’s unfamiliar harmonies, voice leading and cadences can sound exceedingly odd. For anyone willing, Machaut’s music can transport the listener to a very different world, a culture which we might find had very little in common with our own, and that kind of experience can be bracing. The performance of the Machaut, by the Orlando Consort, with bass Robert Macdonald, is exceptionally tonally pure and intimate; the recording sounds like the five singers are standing in a tight circle around the listener. While it’s very unlike the experience of the listener of Machaut’s time, who probably would have heard the singing from a distance, across a vast, highly resonant space, it’s an ideal way for modern listeners to experience the details of the music and the nuanced performance. Guillaume Dufay, who lived a hundred years after Machaut is represented by the motet, Ave Regina celorum, and the popular virelai, Douce dame jolie, sung here unaccompanied by tenor Mark Dobell, a refreshingly straightforward account that contrasts with the frequently tarted-up performances using choruses and instrumental ensembles. Tarik O’Regan takes the Machaut as the basis for a contrapuntally complex and somewhat manic but exhilarating setting for five voices. His Scattered Rhymes is based on fragments from the Machaut Mass, and like polyglot Renaissance motets, use texts in several languages, with the Orlando Consort singing lines from Petrarch in Italian, and with the Estonian Philharmonic Chamber Choir singing English love poetry from the same era. O’Regan has a genuinely original voice; his music is based on an almost incomprehensibly complex layering of polyrhythms, creating a relentlessly driving momentum, but it’s also immediately engaging and friendly, inviting the listener to let go and allow him or herself be immersed in the visceral, sensual experience. Born in 1978, O’Regan is definitely a young composer to watch out for. The performances throughout are absolutely stellar, astonishing in their rhythmic precision, unwavering intonation and interpretive bravura. The sound of Harmonia Mundi’s SACD is comparably fine, with excellent clarity and balance.