NOT MANY groups could update their repertoire by adding tunes from the 19th and 20th centuries, but that is exactly what the acclaimed a cappella women's quartet Anonymous 4 has done with its most recent recording. Gloryland, a collection of traditional American folk songs, spirituals and gospel hymns, builds on the approach introduced two years earlier on the group's American Angels, but with one significant difference. For the first time in the group's 20-year career, it is not alone.

"When the idea come up for doing this second set of American music, I knew that I wanted to have instrumentalists," says Marsha Genensky, who served as the group's music director on both Americana collections. She recruited two well-known Bay Area acoustic string players, Darol Anger (fiddle and mandolins) and Mike Marshall (mandolins and guitar), to augment the vocal harmonies in recording sessions at Marin County's Skywalker Ranch.

It was a comfortable association, Genensky reflects; the two founding members of the Turtle Island String Quartet and members of Anonymous 4 had hit it off long ago when they met backstage at a taping of A Prairie Home Companion. "These guys are so great," Genensky says. "They start with the tradition that we're working with, and then they move on out on to all kinds of wonderful planets of music."

The expanded sonic palette will be on display when Anonymous 4 presents a show called "Long Time Traveling" on Jan. 12 for the Stanford Lively Arts series, accompanied by Anger and with guitarist Scott Nygaard standing in for Marshall.

Genensky says the substitution was not a difficult adjustment. "They're definitely different personalities, but we've come to absolutely love both of them. Mike is a very flamboyant player in a wonderful way," she elaborates. "Scott tends to be more about tone. Each of them concentrates a different way."

The music of both American Angels and Gloryland is predominantly religious, primarily folk hymns and melodies culled from very old church songbooks, including a few familiar songs, such as "Shall We Gather by the River" and "Wayfaring Stranger." This gives it a central commonality with the medieval music that Anonymous 4 is more closely associated with, even though the styles are quite different. But Genensky says that as singers, they approach it in much the same way.

"Really, it's all about singing together and listening," she explains. "It's just a matter of singing different styles. Singing chant is deceptively difficult. Many people think, 'Oh, that's easy. You don't have to sing in parts. You all sing together, it's fine.' But it actually takes the most concentration to sing in unison. That's really different than singing traditional music from America, which tends not to be quite as wide-ranging, tends not to require the same level of exactitude."

Despite their name, Genensky and colleagues Susan Hellauer, Jacqueline Horner and Johanna Maria Rose are readily identifiable. In a departure from their historic process, which was collaborative, Genensky took an individual lead role in the preparation for Gloryland, primarily because she spent the past year as a visiting scholar at Stanford, while the other three singers remained in New York. "We tweaked it together, but it basically was how it was by the time I got to everybody," Genensky agrees. "We made a couple of the arrangements together. But many of the arrangements are by me, and by the instrumentalists. So that's new for us." And Genensky adds, she derived pleasure from hunting down the old songs. "If you ask me in the moment where I'm sticking my nose through thousands of pages of 19th-century tune books at UCLA special collections or at Yale ... I'd say, 'Oh, this is so great, I can't stand it.'" She laughs. "But then when we're actually singing, I'd say, 'This is so great, I can't stand it.'"

Anonymous 4 performs Fri., Jan. 12 at 8pm at Dinkelspiel Auditorium, Stanford. Tickets are $18-$40. (650.725.ARTS)

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