Christmas time is here, by golly. Time to mix a punch of Baroque orchestral music, sacred vocal music of various periods, and a medley of Christmas carols and Hanukkah songs. That's what the New Century Chamber Orchestra served up for its December concerts last weekend. I heard Friday's performance at First United Methodist Church, the "concrete tent," in downtown Palo Alto. It would do anybody's heart good to hear soprano Melody Moore sing the contemporary American composer Morten Lauridsen's hauntingly beautiful setting of the old Latin text O magnum mysterium. (The composer's voice-and-piano version of this motet was tastefully arranged for voice and string orchestra by NCCO's "Featured Composer" of the season, Clarice Assad.) Moore has a remarkably controlled voice that goes from meltingly soft to the height of emotion and projection without strain. Her full vibrato is so constant that it becomes a feature of her tone and not an effect. This was a riveting performance, with the touch of a memorable rendition of one of the great Italian tragic opera arias. Fine sounds also came from the 16 singers of Schola Cantorum San Francisco. Their artistic director, Paul Flight, led them in two short a cappella Noel motets by Renaissance composers Pedro de Cristo and Antoine Brumel. He then joined the other two male altos in the chorus for a somewhat larger choral work with orchestra, by Buxtehude, Das neugeborne Kindelein. All three works were light and cheerful — Cristo's Quaeramus cum pastoribus (Let us seek with the shepherds) was particularly light, as it has no bass part — with a pure, clean tone and rich balanced harmonies. Brumel's full contrapuntal setting of the single word Noe (Noel) was the finest of the works. The grand finale involved everybody — solo soprano, chorus, and orchestra — in a medley of holiday songs chosen by NCCO Music Director Nadja Salerno-Sonnenberg and arranged by Assad. The 10 carols, songs, and blessings in six languages covered various forms of the Christmas and Hanukkah spirit. Some pagan solstice carols, and maybe a few Kwanzaa songs, would have made it even more ecumenical, but we take what we can get. This medley was complex enough that Salerno-Sonnenberg had to conduct parts of it outright instead of just leading with her bow while playing the concertmaster's part, as she otherwise did. Assad put a lot of imagination into the vocal and instrumental arrangements. The violins uttered donkey brays à la Saint-Saëns or Mendelssohn at the reference to the manger in In dulci jubilo, and the 1950s Caribbean-style Christmas song Mary's Little Boy Child slowly runs out of steam at the end, like Villa-Lobos' Little Train of Caipira. The performance was comfortable and enjoyable — Moore was especially moving in the Hanukkah candle-lighting blessing — but the singers were not as commanding as in their core repertoire. The gentility that served them so well in the sacred motets doesn't really fly in lively Christmas songs and carols like Mary's Little Boy Child or Deck the Halls.