When bass player Kellen Shiles was asked to join what would become Chattanooga-based outfit Masseuse, he brought cello player Ben Van Winkle along for the ride. The two had a musical history dating back to high school, and Shiles felt certain that Van Winkle’s clever use of effects and adaptive capabilities would be big assets for his budding new band.

“I always loved the way Ben played, and I knew I wanted to continue playing with him,” Shiles says. “The songs he comes up with, his musical ideas fit in really well in a rock context. So when I met the other guys (in Masseuse), I was like, hey, I know this cello player. And they decided to roll with it.”

That was roughly five years ago in Murfreesboro, where the Masseuse members met as students at Middle Tennessee State University, before the band took off and relocated to Chattanooga. Shiles says he and the other six members initially bonded over their love of jam bands — especially Phish — thus sparking a loose-knit musical collaboration centered around rehearsal room improvisation.

“It was not very strict,” he says. “We’d write songs by jamming around on ideas. Someone would say, hey, that sounds like a verse. And then our singer (Ross Lenenski) would write lyrics.”

But something happened as Masseuse began playing more often, evolving from a part-time creative outlet to a serious touring entity. Their songwriting became correspondingly more disciplined, as band members integrated prog-ish structures with alt-rock hooks. The result was a sort of virtuosic and compositionally daring brand of long-form rock that plays as well on record as it does on stage, an alt-jam hybrid not a little reminiscent of Phish’s 1996 songwriting breakthrough “Billy Breathes.”

“Yeah, our songwriting has gotten a whole lot more sophisticated,” Shiles acknowledges. “Our early songs were essentially just jams. Now, we do more writing on our own — all of us contribute pretty significantly that way — and then we collaborate on those ideas once we get together. We come up with full-fledged ideas on our own, and then tighten and embellish as a group.”

Adding to the mix, of course, is Van Winkle’s weirdly versatile cello. “He does some cool stuff,” Shiles says. “He runs his cello through different effects pedals, and comes up with all kinds of ambient and psychedelic sounds.”

But though they’ve released a slew of singles and videos on the Internet, Masseuse have yet to release their first proper album. That should change soon, as the band is prepping to put out a full-length debut “Ambidextrous” in March.

“One thing we want to do is make sure the record offers something different from our normal live show,” Shiles says. “We changed up some instruments, changed up some arrangements, added percussion.

“We’ve got a couple songs that have more of a world-beat feel to them, ideas that we had swimming around that now we can finally make come to life. Our idea was to do things that would really make this record unique, and then we’ll figure out how we can replicate most of it live.”

Masseuse will play Preservation Pub Saturday, Dec. 30 at 10 p.m.