Christmas began on Sunday night when Chanticleer sang its annual concert in front of the big tree at the Metropolitan Museum. Or so it seemed to me. The 12-man group from San Francisco, which performs a cappella, gives this concert annually. Actually, they are singing the concert six times this year, and all of those concerts are sold out. How many more could they sell out? Maybe the market should test it.

In any case, it’s encouraging that the public knows a good thing when it sees one, or hears one.

As usual, Chanticleer provided a nice assortment of Christmas music: from different periods, in various styles, and in various languages. The Christmas repertoire is inexhaustible, and of strikingly high quality. Chanticleer is of strikingly high quality, too: They sang well-nigh impeccably.

They have great unity and discipline: I have noted that they even open and close their books together. Their voices blend nicely, with the highest ones refusing to dominate, although they could. They have exemplary intonation, rarely veering off pitch in the course of an evening. They could give many an ensemble — vocal or instrumental — a lesson in intonation. Some individual voices in the group are better than others (obviously); but they make up one, choral voice.

I could go on about Chanticleer particulars, especially technical ones. But the important thing is the feeling they give forth, the musicality they embody. It’s hard to be unhappy around Chanticleer.

Sunday night’s concert began with “Natus est rex,” from the 12th century. It is a chant, containing one vocal line. When the boys moved on to a 16th-century motet — Jean Mouton’s “Nesciens mater”— it was as though the sun had come out. All that harmony! And inexpressibly beautiful.

Also extremely beautiful was a piece of Gabrieli — no, not that Gabrieli, the brass-choir man, but his uncle, Andrea Gabrieli. This piece was “Quem vidistis pastores?” wherein shepherds give their glad report — and there was gladness in Chanticleer’s singing.

What came next was a high point of the evening: two “lauds” from 13th-century Italy. “Altissima luce col grande splendore” was amazingly soft, gentle, and delicate — but, somehow, not fey or fragile. The following laud, “Venite a laudare,” was robust, and you could even say lusty. Besides which, Chanticleer flavored it with the blues, I swear.

In “O Jesulein süss! O Jesulein mild!” — that emblematic German piece — the group sounded like some perfectly balanced organ. Their “In dulci jubilo,” however, could have been far peppier, in my opinion. It was unreasonably sleepy.

They sang one piece of Arvo Pärt, the magnificent Estonian composer, recently turned 70. It is in German: “O Morgenstern.” And it is a lovely, well-crafted, inspired work, as you can expect from Mr. Pärt.

In the center of the program was César Cui’s Magnificat, Op. 93, which Chanticleer has sung before in the Met Museum. Is that cheating?

Whatever the case, the group performs it with heart and pleasure, and you can hardly blame them for repetition.

Thereafter they sang some familiar carols in English, starting with “Ding Dong! Merrily on High.” That was smooth, smooth, going down easy. “It Came upon a Midnight Clear”was pretty — but very slow, and too subdued. That carol is soothing, but not a sleeping pill. Chanticleer made up for it with “God Rest Ye Merry, Gentlemen,” in which they were a model of unison singing — as much as in their opening piece, from the 12th century.

As the evening wound to a close, Chanticleer’s music director, Joseph Jennings, came out, to join his group. What they sang was a gospel medley of his own arranging. Mr. Jennings has a wonderful gift for this — and his latest medley is joyous, slick, catching. Full of praise. As Mr. Jennings was singing/preaching, I felt like raising my hand — but the setting was wrong.

And then — you could set your clock to it — Chanticleer sang its signature encore, the Ave Maria of Franz Biebl. I believe they sang it too slowly and bloodlessly. They must take care not to get precious with it. The piece needs body and life, and forward movement.

But never mind. This was a deeply gratifying concert — a great concert. I’m afraid I lack the words to describe it properly. I will say what I’ve said before: Chanticleer is spiritual substance in an age of watery “Happy Holidays” gruel. Theirs is a concert about Mary, Joseph, and Jesus. These guys “name the name of Christ” more than is done in most modern churches, I believe.

And their audience is the quietest of the year, in any venue. You could hear a pin drop as Chanticleer sings. And then, when they’re through, the audience explodes.

Better get your tickets for Christmas ’07, and get ’em early.