Matt Johnson and Kim Schifino were playing in a completely empty Chop Suey around 6 p.m., testing their instruments for the sound check, when Johnson jumped down from the stage and hollered at “Dan Dog,” the roadie, to take over.

“This is the first time I’ve ever heard us from the audience,” he mused. “We sound good!”

After a few more practice tracks, the Brooklyn indie-pop duo and I migrated to the venue’s back room. It’s Johnson’s birthday, and they’re trying to get to dinner before the show. Schifino did an online search: it’s either Hot Mama’s Pizza or the Cha Cha Lounge. Oddly, their last stop in Seattle happened to be on Schifino’s birthday.

“I’m glad to be playing a show,” Johnson said. “For me, birthdays are pretty depressing. I don’t know why it is. I can’t figure it out, I just get depressed. So actually, a show is something that brings my spirits up.”

Champagne Champagne was not the type of act I would’ve expected to open for the power-pop headliners. Their synth-backed rap performance wasn’t unpleasant or lacking rhyme flow, but it was an unexpected warm-up for a crowd prepared for Matt & Kim’s brand of pop. Politely, though, the calls for “last song!” were kept to a minimum.

When the duo finally crept onstage and snagged their stools, the explosion was not only audible, but tangible. Kim kicked off with some throbbing drum work, and as much as they hate being pegged as a “cute band,” the duo’s gigantic smiles and upbeat melodies were helplessly infectious.

“How many times have you gone to see a band because someone told you they were cute?” Schifino asked. “I’d probably want to hit the band.”

“The thing is, we’re going to be how we are, no matter what,” Johnson said. “I’m a firm believer in bands being honest when they play. Kim and I are always psyched to play, and if that turns into cuteness, I guess that’s what it turns into.”

The concert was a party in the most basic sense. Schifino banged out her speedy, double-pedaled bass rhythms and Johnson laid his bouncy right-hand melodies over the top. Though they began playing three-song opening sets when they first toured a few years ago, this past Thursday, Matt & Kim played almost all of their popular tracks, including “Daylight” and “Good Ol’ Fashioned Nightmare” from recent sophomore album Grand and “Yeah Yea” from their debut self-titled release.

They closed with “Silver Tiles,” and near the end Champagne Champagne snuck onstage with balloons and a birthday cake. After blowing out the candles, Johnson smeared chocolate cake and vanilla frosting on his face, then dove into the crowd.

“Encores are one thing we just don’t do,” Schifino said. “They’re like an ego-stroke to the band, like they’re going to want us back. Our encore is to start a crazy-ass dance party, just to jump down and dance with the crowd. Seattle’s got some work to do tonight.”

Reach reporter Nick Feldman at arts@dailyuw.com.