The Mastersons aren't particularly familiar with the idea of "downtime" anymore. Part of Steve Earle's band the Dukes and a duo themselves, husband and wife Chris Masterson and Eleanor Whitmore moved to Los Angeles, Calif., in October -- they're also session musicians, so living in LA means more opportunities to do that and still be able to go home at night -- but they won't be around much in the coming months. Masterson and Whitmore will be hitting the road with Earle, in support of his forthcoming new album, So You Wannabe an Outlaw, and they're also touring on an album of their own, Transient Lullaby, out Friday (May 19).

"Our life seems so crazy sometimes," Whitmore admits. Adds Masterson, "You never stop. And that's good, and we love what we do, and we're really lucky to be doing it, but we kind of never stop."

Originally solo artists, Masterson and Whitmore got married in August of 2009, started playing with Earle in late 2010 and released their debut album as a duo, Birds Fly South, in 2012. As Masterson tells The Boot, "Working full time with someone you're intimately involved with us a full-contact sport," and although they've tried to set boundaries and off hours, "we're either writing or traveling or tending to something ..."

It's Earle who gets much of the credit for putting the Mastersons together, musically speaking. When the two became part of the Dukes, Earle suggested that they start getting some material together so that he could feature them during his shows; the couple was already writing together and had been toying with the idea of officially forming a duo, "but [Earle] kind of lit the fire under us," Whitmore says.

"It couldn't have happened more organically; I couldn't have dreamed that up," Masterson says. The Mastersons funded Birds Fly South themselves and invited their friends to play on it. Then, "momentum sort of built itself," Masterson recalls: They sold the record at Earle's shows, "and it picked up a little steam;" New West Records came calling, and "it all just sort of happened."

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Now with Red House Records, the Mastersons penned nearly all of Transient Lullaby's 11 tracks alone and all over the world -- both byproducts of being on tour. Album opener "Perfect" came to life in Washington, DC; "Fight," in Cleveland, Ohio. "You Could Be Wrong" started in Lexington, Ky., while "This Isn't How It Was Supposed to Go" was written in Cologne, Germany.

"You can [co-write] long distance," Whitmore notes, "but I guess we just didn't feel the need to do it this time around."

Despite their hectic schedules, the Mastersons say they never feel as though they have to try too hard to write; they have to force themselves not to create something good, but to unplug and center themselves.

"Our phones are full of a bunch of cool ideas," Masterson says, "but it takes time to sit with them and embellish on them and let them mature into something more than just a cool idea."

Transient Lullaby's lone co-write comes on "Highway 1," which the Mastersons wrote with Canadian singer-songwriter Steve Poltz ("He's a hoot," Whitmore says). The song is actually a leftover from their last album, 2014's Good Luck Charm: It didn't quite fit with the rest of that record's material, but the Mastersons started playing it live; it became a fan-favorite and, Masterson and Whitmore realized, would fit perfectly on their newest project.

"Every record [we've made] has had a West Coast reference here and there," Masterson notes, so "Highway 1" checks that box for Transient Lullaby. "Though it was in the pile of songs for the last record, it never felt like a B-list song."

Working full time with someone you're intimately involved with us a full-contact sport.

Transient Lullaby also includes a number of songs that Masterson describes as "cosmic country" or "stoner country": songs that began as traditional country tunes, then morphed into something a little bit different. "Perfect" is ... well, a perfect example, with a retro melody reminiscent of 1960s British rock 'n' roll. The song "lived one life" and even appeared in the Mastersons' live sets for a bit, but for the studio version, they re-worked it.

"We're definitely a product of our roots ...," Whitmore explains, "but we've always been fans of the Brit bands and the Beatles and the Kinks."

In addition to learning from their idols, the Mastersons have been able to pull lessons from the sidelines as they work with other artists. Masterson and Whitmore say its pretty easy to switch from the roles of frontman and -woman to that of sideman and -woman; naturally, Whitmore says, "it's a lot easier being a sideperson!"

"What [being a duo] has given us is, certainly, a profound respect for everyone I've ever worked for," Masterson continues. "Even the bad ones!"

Three records in, though, the Mastersons are "a lot more comfortable in our own skin."

"I think we kind of know how to be the Mastersons," Masterson says. "Whatever that is."

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