On one chilly February night in a loft show in Somerville, the lights went out on Mount Peru. The eclectic band — part driving alt-rock, part backyard country — forged ahead in that dark room of locals, summoning campfire courage and makeshift charm for what ended up being one of its best sets ever. Frontman Thom Valicenti says it was a stripping down that ended up leading them to a new comfort zone. “I feel like we got to be super-relaxed that way,” he says. “It seemed like we were really in our element.”
Mount Peru has been through a lot of changes over its five-year existence, during which the group has released an album and a couple of EPs. The band’s approach has been full of deliberate musical switchbacks, going from barroom rock ’n’ roll to trumpet-led indie-rock and back again, plowing through lineup changes in the process. The band has been nominated for local Americana awards and experimented with ’80s synths in the studio. But with their easygoing new EP, “Is This Thing On?” (the release of which they’re set to celebrate next Thursday at T.T. the Bear’s in Cambridge), it sounds as if the band is finally settling in.