The idea for Well-Strung, a singing and string quartet, was born in Provincetown. While visiting the Cape for a different show in 2010, violinist Chris Marchant was playing on the street for extra money when he was approached by producer Mark Cortale.

“He saw me singing and playing,” Marchant says, “and asked me if I wanted to collaborate on an idea.”

The idea: to combine pop music with traditional string quartet playing. Based in New York City, Marchant began the search for the three other musicians. He met cellist Daniel Shevlin on Facebook. Violinist Edmund Bagnell and violist Trevor Wadleigh answered an audition call.

Behind the judging table, “we were checking to make sure people were performers and captivating in the way they interacted with the world,” Marchant says. Bagnell and Wadleigh stood out in an almost imperceptible way, he says. They had an ineffable talent. The group, all four of whom are gay, did their first show in Provincetown in 2012 at the Art House.

Marchant studied music at Malone University in Ohio but knew he wanted to “sing and keep playing in New York.” His teachers weren’t very supportive. “My vocal teacher said, ‘OK, well go ahead and get that out of your system,’ ” he says. “I was like, ‘Are you kidding me? I’m going to do this.’ ”

He found a new teacher and began to really “put in the woodshedding work” on the violin. The other musicians in the quartet received high-level classical training in post-grad programs, conservatory, and college.

Playing in Well-Strung isn’t a primary job for these musicians. Wadleigh and Marchant work together at the McCarton Foundation, a nonprofit that provides therapy for children with autism. Bagnell and Shevlin have their own solo careers. But the four still come together occasionally for reunions like their upcoming holiday show at Provincetown Town Hall on Saturday, Dec. 30.

At the peak of their full-time touring career, which lasted five years, the four formed a close and long-lasting friendship. “For several years we lived in a four-bedroom together,” Marchant says. “It was our workshop where we’d rehearse new material. We’d fly to our concerts together and then all come back home together like a family.”

As for where they performed: “I wish there was any rhyme or reason to it,” Marchant says. “Mostly, anybody who called, it was, ‘Here we come! We’re hopping on a plane!’ ” The group was playing around 100 shows a year: 30 over the summer in Provincetown and 70 in the off-season.

Their pop-classical repertoire is all arranged by the quartet members. After one presents an arrangement idea to the others, the group will “hash it out and make marks, suggestions, and alterations,” says Marchant. Then the brunt of the arranging falls on the one who posed it. “At this point, everyone’s arranged about a quarter of our material,” he says.

The group also makes mash-ups, fusing two songs into one, usually of pop hits with classical staples, like “Creep / Ave Maria,” “21 Guns / Pachelbel’s Canon,” “Paparazzi / Vivaldi’s Winter,” and “Perfect / Jesu, Joy of Man’s Desiring.”

All four members of Well-Strung can sing and play their instruments at the same time, which Marchant describes as similar to “rubbing your stomach and patting your head.” The uncanny skill is “absolutely crazy and nobody should attempt it,” he says. “It’s unnatural.” But the music that they produce sounds anything but unnatural. It’s complicated yet balanced, and very clever.

Both “Creep / Ave Maria” and “Paparazzi / Vivaldi’s Winter” are on Well-Strung’s 2018 album Under the Covers. In their arrangement of Radiohead’s famous song, fast-plucked violin is the undercurrent for the lyrics. At the song’s peak, the violin floats above the vocal turmoil. Hints of “Ave Maria” are present but not overpowering. As for Lady Gaga, she comes together with Vivaldi in perfect harmony. The dangerous tone of “Paparazzi” complements the frantic feeling of Winter. Well-Strung demonstrates exceptional classical skill yet manages to sing in the pop style.

At their upcoming show, the group will play both of those songs, along with a mix of “traditional Christmas rep, off-the-beaten-path stuff, and regular mash-ups,” Marchant says. Instead of viola, Wadleigh will play as a third violin “because of the singing that’s involved,” Marchant says. “Sometimes it’s necessary to keep more violins at the top, depending on who’s singing.”

Since their shows together are now infrequent, each time the group gets together “it’s really a treat,” Marchant says. He recalls the first time they began to forge their bond: after being offered a cruise ship gig, a snowstorm canceled their flight. “We rented a van and drove from New York to Florida,” Marchant says. “We didn’t really know each other well yet. It was weird, but it was wonderful.”

The group has evolved since then. “Ten years ago, I would have said we had a two-year shelf life,” Marchant says. “But we really found a musical identity together that has a much stronger foundation than any musical gimmick we could have come up with.”

Well-Strung has 12 years of history to draw on, which is apparent in the way the group collaborates so well on and off stage. “Edmund always says it so beautifully,” Marchant says. “We’re the only four that have been at every show we’ve ever done.”

Make It New

The event: Well-Strung holiday reunion show
The time: Saturday, Dec. 30, 7:30 p.m.
The place: Provincetown Town Hall, 260 Commercial St.
The cost: $50-$100 at ptown.org