Alt-J performs on the Honda stage at ACL Music Festival on Sunday, October 4 2015. (Suzanne Cordeiro / For American-Statesman)

Alt-J is like when you have a reservation at Midnight Cowboy and the craft cocktail barkeep makes you a drink while explaining its unique ingredients: Yeah, I guess that’s an interesting aromatic buzz.

Sunday evening at the Honda Stage, the Leeds, England, the band filtered influences through windowless, driving alt rock. Just beyond the cluster of believers, some napped in peace.

In 2013, former bassist Gwil Sainbury told me about how he helped forge an accessible rock band from singer Joe Newman’s distinct, richly spastic and chirpy singing voice.

“We understood it was a fairly strange [record], not easily digestible, and we didn’t have any sort of expectations for how it’d go,” he said at the time. He continued:

“It was about a year of [MacBook recording software] Garageband,” Sainsbury, who left the band amicably a year later, said. “I was one of the first people that Joe sort of sang in front of… it was unique even back then. It was shocking and I remember thinking it was quite strange, relative to how he speaks. We thought about it more as an instrument, in fact I didn’t think about his lyrics until I read the album sleeve and noticed some of the dark stuff that was buried there.”

Since then the band has become a national fixture across modern rock radio. I’m at a loss as to why.

The most recent record, 2014’s “This Is All Yours,” wades in static tempos full of industrial, cold-clanking drums and subtle guitar lines. The all-black, cranky aesthetic was briefly interrupted by a fan-made flag that caught them in a fit of laughter. It was the most joyful moment of the festival. (I think it was profane.)

Alt single “Hunger of the Pine” samples both Miley Cyrus and quotes French poet Alfred de Musset. Cool story, bro. This is a band full of intelligent college buds, and rocks like students who sit in circles and play a Jenga game of name-dropping.

The know-it-alls closed with 2012’s “Breezeblocks,” the band’s breakthrough moment of clarity. This paper plane melody lands–its barreling bass, spooky bells, and Facebook-stalker pleads made the grounds swoon and recite its “please don’t go, I love you so” breakdown.

Few more of those and we’ll see them at the next album cycle.