Eduardo Mendelievich is a music director who clearly isn't afraid of dynamic variation and vigorous tempi. The ascending, imitative lines of the Kyrie raced along under Mendelievich's clear direction. In the Gloria's "Domini Fili" section, the chorus showed a clear sense of line, the dynamics following a dramatic arc. And the "qui tollis" section slowed down into a hushed "suscipe." The altos, bolstered by a few tenors, stood out from the rest of the choir with a warm and satisfying tone.

At times, however, especially later in the Gloria and during the "hosanna" section of the Sanctus/Benedictus, I wished for less of a singsong, dramatically marcato effect, the result of too mindful counting of the beats and not enough attention paid to producing an even fluidity to the line. It's possible to be both expressively vigorous and musically level, while still keeping the audience awake. Things turned around dramatically in the Agnus Dei, however, when the trademark straight singing style of early music returned to the placid lines of the final "dona nobis," leaving the harmonies hanging completely still in the air. It was an extremely moving ending.

In the second half, two diverse pieces stood out among the scattering of songs: Mateo Flecha's pentecostal El Fuego and Clément Janequin's onomatopoeic Le Chant des Oyseaux. El Fuego is a raucous celebration of Spanish rhythms, with full-throated cries of "¡Fuego, fuego!" (fire, fire!) and orders for sinners to pour on buckets of repentance. The piece shifts abruptly at the end, changing into church clothes to deliver a dignified conclusion in Latin. Le Chant des Oyseaux, on the other hand, mixes the sounds of birdsong with a catchy melody that repeats throughout the piece. In both works, the chorus was confident in its abilities, not always a common trait in amateur choirs, and brought out the emotion of what can be busy pieces.

A pair of familiar Monteverdi madrigals, Lasciatemi Morire and Ecco, Mormorar L'onde, showcased the choir's full, rich sound, especially in the gorgeous descending lines that build to the final "lasciatemi morire" (let me die). The opening motets to the concert were Ave Dulcissima Maria and Deus Refugium et Virtus by Carlo Gesualdo, the aristocrat who killed his wife and her lover and got away with it. Characteristically for Gesualdo, the tortured and unusual chromaticism was scattered amid moments of sheer tranquillity. For a spirited encore, the choir sang two songs from its recently released CD of choral tango arrangements, if that can be imagined, titled "El Ultimo Cafe" by Catulo Castillo and Héctor Stampone and "Calambre" by Astor Piazzolla. Here the choir sounded at home, with a tight sense of ensemble and a clear enjoyment of the toe-tapping music.

The Bay Area is crowded with amateur choirs. Only occasionally does one rise to a more professional level, through a combination of natural talent and skilled direction. Creative Voices has all the usual things you want in a choir — confident singing, good tuning and balance, and a focused sound. They add to that high standards, attention to detail, and even more rare, a passion that sets them head and shoulders above the crowd.