Guy Marshall, video courtesy of Live and Breathing

Knoxville’s Guy Marshall have seen a couple of significant sonic evolutions since their founding three years ago. But the beating heart of the band’s sound is still the cry-in-your-beer harmonizing of husband and wife songbirds Adam and Sarrenna McNulty, and that sets G.M. in good stead for just about any path they may take in days to come.

The band began as a duo—sort of—when Sarrenna encouraged her newlywed husband to showcase his songwriting talents at a Maryville coffee shop. Both Adam and Sarrenna had experience playing and singing before an audience before—albeit not as original artists—at Trinity Chapel, the North Knoxville church where they met as young teenagers.

At that first coffee house show, Sarrenna joined Adam for a couple of songs. The experiment went well enough that the pair played together again in Knoxville; they soon earned invitations to perform live radio sets at the University of Tennessee’s FM 90.3-WUTK, and local Americana non-profit WDVX (FM 102.9 in Knoxville.)

And they started adding band members, including singer/stringman Eric Griffin, another childhood church pal, and Adam’s first guitar teacher. “A lot of my first influences were just whatever Eric put in front of me,” Adam chuckles. “For a long time, that was British pop, and a lot of Radiohead. And then southern rock—I still think ‘Tuesday’s Gone’ [Lynyrd Skynyrd] is one of the greatest songs ever written.”

But in spite of McNulty’s assimilation of various modern and classic rock artists, there were other, deeper influences at work in shaping the band’s direction. The name Guy Marshall offers a clue: “My papaw’s name was Guy Marshall Shirley,” Adam says. “There were a couple of early songs about him, and some about the history of our family. And it’s such a badass name. It all just seemed to fit.”

Papa Shirley loved bluegrass, as did many members of McNulty’s immediate family. Adams says some of his earliest memories are of singing along to Alison Krauss records, when he was scarcely past toddlerhood. Those experiences told, once Guy Marshall came together.

In fact, the band’s earliest inclinations were toward bedrock country and traditional mountain music. “I was big into old-timey music for a while,” McNulty says. “Even though I loved rock, I was never comfortable writing anthemic kind of rock songs. This was an area I felt comfortable writing in.”

Though some rock influences eventually crept in, G.M. took a turn back toward its rural southern roots in the last year or so, especially after the addition of local guitarist Jonathan Keeney on pedal steel.

“This is by far my favorite mash-up of sounds we’ve had through about three different incarnations of this band,” McNulty says. “Lately, we’ve been diving really deep into outlaw country and honky-tonk, Waylon Jennings and Merle Haggard. It’s been a whole lot of fun, especially after Jonathan came in; those old honky-tonk guys always had a pedal steel in the band, and Jonathan really jumped on it.”

But for all the yearning, heart-on-sleeve poignancy of the band’s live set, Guy Marshall is still woefully behind the curve as a recording act. Right now, the band has only one demo to its credit, dating to the first few months of its existence.

McNulty says the band’s repertoire has expanded, despite the lack of recorded output. “We have enough material for a couple of albums; we just haven’t laid it down,” he says. “But we’re getting to a place where everybody’s confident with the songs, where everybody knows it has to be done.

“A lot of our holding back has been due to me. I second guess myself a lot. But we’ve been evolving into something else, and that’s part of it, too. I like what we’re doing better than ever now.”

Guy Marshall will play Scruffy City Hall Friday, July 25 with Atlanta country-rock outfit The Whiskey Gentry. Show starts at 10 p.m