I caught the Austin band Sweet Spirit by accident at last year’s SXSW—I had dropped into an early-morning show by Sharkmuffin, and got caught up in the crawfish boil happening out back. On stage was a very large group of people wielding both electric and wind instruments, wearing eclectic outfits, looking like a white Sly and the Family Stone. The weird thing was that they kind of sounded like that, too. My notes are full of question marks: “some wild giant band, a 9- or 10-piece,” “horns, serious instrumentation,” a track that went from nothing, with quiet vocals “to slamming, with giant vocals/horns chord,” and a “drama queen” for a front-woman. “Arcade Fire? Pop? WTF?” What the foxtrot, indeed—what I didn’t know is that Brit Daniel of Spoon had already discovered Sweet Spirit, and they had landed the SXSW gig without even a record to promote. They then toured with Spoon and were quickly going from unknown to notorious.

Singer Sabrina Ellis started Sweet Spirit as her previous band, Bobby Jealousy, fell apart along with her marriage to a bandmate. She was still performing with the garage punk band A Giant Dog. “It was supposed to be focused on me writing solo, and performing with the guitar,” she says in press notes, but soon she was writing songs with A Giant Dog co-founder Andrew Cashien and playing around town got them noticed. Their new album, St. Mojo, which came out April 7, was produced by Steve Berlin and features guest performances by members of Grupo Fantasma, Mother Falcon, and A Giant Dog, to go along with the already substantial 9-piece line-up.

Preview track “The Power,” which Ellis describes as “the underscore to our freak parade,” weaves a soulful funk groove with a grunge hook—in the first 20 seconds. Ellis’s voice drops in like a lost track from the Gogos—or, perhaps, a Joan Jett record. And then goes full-on Lyn Collins spoken-word, about getting a Dorothy Hamill haircut—which is just so hipster it would sting if it weren’t so effective.

The press snippits littering the band’s website are all equally fawning, though they appear to be written about several different bands.

While music listeners everywhere seem to have accepted the fact that genre is, at most, a spectrum, music journalists are still catching up to the idea, since the very act of writing about music necessitates a comparison to a sound the reader may have heard before. In a recent New Yorker article, Amanda Petrusich defined musicians’ YouTube access to all of musical history as the latest iteration of what was once the domain of crate-digging DJs: “In the Internet age, this is how almost everybody listens to music, minus the dust: songs arrive free of circumstance. For artists working today, records from any time and place are easily juiced for inspiration.”

If Ellis and Sweet Spirit’s goal is to make a mashup of conflicting influences feel like an original sound, they’re succeeding, and if that’s not what they were going for, they’re still pulling it off. Tonight at Rough Trade, it will be interesting to see if they’re able to achieve the impossible: getting a New York rock crowd to dance.

Bradley Spinelli is the author of the novels “The Painted Gun” and “Killing Williamsburg,” and the writer/director of “#AnnieHall.”