David Wax Museum becomes a family band

When David Wax Museum first emerged on the national Americana scene in 2010, it felt like an exhilarating step forward for American roots music. Effortlessly blending Mexican folk elements and instruments into a mix of Appalachian old-time and modern indie rock, David Wax and Suz Slezak seemed to intuitively understand how traditional music should grow and evolve in the 21st century. Widely acclaimed for their live show and Wax’s studied songwriting, the duo won rave reviews and accolades for their relentless touring and the two elegantly rugged, mostly acoustic LPs that preceeded their breakout.

Since then, the band has released two increasingly eclectic and fully realized but less Mexican-influenced albums produced by Sam Kassirer (of Josh Ritter’s Royal City Band), gradually expanding into a five-piece live act that’s more fully equipped to handle its newer material. The group has also continued to tour the world, including a stint as cultural ambassadors in Shanghai.

These days, though, the biggest change has been a small thing — the birth of Calliope, Wax and Slezak’s 6-month-old girl. Both Calliope and Slezak’s father now tour with the band. “The best part and the biggest difference is just the mood in the green room,” says Slezak. “Not that it was ever a big downer to hang out with the band, but to have three generations of family touring makes the mood sillier, lighter and a lot more fun.”

The flush of excitement and joy in her voice over this latest turn in her and Wax’s life is palpable, mirroring the charismatic energy the duo have consistently brought to their live shows. For Slezak, who always envisioned a life outside the box, there’s a decidedly liberating aspect to the traveling-family-band lifestyle. “I really love the idea of having my family and my career as one picture, not as two separate things, which is not a possibility for many women,” she says. “It was really important to me to somehow incorporate the two. I feel extremely lucky to be able to do that.”

The gypsy-family approach also seems to suit the band’s expanded lineup, which includes Wax’s cousin Jordan on accordion and keyboard as well as drummer Philip Mayer and electric bassist Greg Glassman. “We call all the guys in the band ‘road uncles,’” says Slezak. “The baby gets a lot of affection.”

The additional band members also underscore the group’s edging away from its early Mexican influences, something Slezak says she and Wax are keenly aware of. “In some ways, we are questioning what role the Mexican influence should have now,” she says. “We’ve been a band for seven years, and we’re wondering, how important is that Mexican piece? Does it have to be there? Probably, because it’s still an inspiring sound that fuels our excitement about the band, but that element is still evolving in our music.”

Slezak is also quick to point out that these questions haven’t so much shifted as expanded what the band is capable of. “It’s not as if we don’t still pull out our Mexican instruments and get around one mic and serenade the crowd acoustically,” she says. “We still do that. But the songs are bigger and more exciting with the rock band lineup, and we still have the flexibility to come down in the audience and play for people up close. There is just more depth and variation to the shows now.”

As self-proclaimed purveyors of a “Mexico-Americana sound,” the duo’s ambivalent attitude toward its melting pot of roots and rock styles might sound a little flimsy on paper. But Slezak reports that Wax has been busy writing songs for a new record that “will ask all those questions again: How obvious is the Mexican influence? What does it mean? What does it need to be?” And meanwhile, the power of the music itself, particularly 2012’s Knock Knock Get Up, speaks volumes for how natural — and powerful — the group’s sure-handed evolution has been.

WHO David Wax Museum

WHERE The Millroom, ashevillemillroom.com

WHEN Wednesday, June 18, at 9 p.m. $10 advance/$12 day of show