Crammed into a dressing room before their biggest gig to date, an opening slot for the Get Up Kids at Toronto’s Kool Haus, the fresh-faced boys and girls who make up the Most Serene Republic initially come off as a high school band in the midst of making very, very good.

Still living with their parents, it’s not been long since most members of the Milton-based collective were still in classes, scheduling occasional practices around their homework. Now, their debut album is being re-released to a broader audience, they’re touring the United States opening for Stars, and they’re playing this Sunday’s Toronto Island show on the same bill as Broken Social Scene, Modest Mouse and Metric. Hyperactively cutting off each other’s sentences and good-naturedly teasing one another, they’re clearly giddy from all the buzz they’ve been getting.

“I’ve never been anywhere,” says Emma Ditchburn, the band’s lone female member, when the subject of their first tour is brought up.“So I’m really excited.”

Then they’re asked about about the similarities to Broken Social Scene. It’s an inevitable, oft-repeated query given the obvious musical influence, the similarly hap-hazard collaborative approach and instrumentation (singer Adrian Jewett doubles as trombonist), and their recent signing with the heavily BSS-associated Arts & Crafts Records. But when keyboardist and principle songwriter Ryan Lenssen launches into an out-of-left-field classical music analogy, it speaks volumes about a band that’s far more serious in its interests and ambitions than its light-hearted demeanour would suggest.

“Someone once listened to Brahms and said ‘wow, you sound just like Beethoven,’” he begins. “What did Brahms do? He tore up his music and threw it in the fire. Dude! Someone said you sounded like one of the best composers of all time. I understand the frustration, because we all want to be individuals, right? But you have to start somewhere. And if you can reach the genius of someone else, and then go in a different direction, I think that’s the top one that you can possibly have.”

On the sudden ability of non-mainstream acts like his to break through, Lenssen offers a dissertation on indie music’s cultural significance. “I think that the one true art form that is really coming from North America is the idea of indie rock,” he says. “The major labels are having a tough time right now, because people who are listening to music are getting tired of 4/4 time, they’re getting tired of power chords, they’re getting tired of melodies that are clear rip-offs of Yes and the Who and the Beatles.”

The goal of bands like MSR, Lenssen suggests, is to get away from “a pop culture that completely assimililated music, instead of music changing the way we were thinking.”

As their classically-trained keyboardist gets serious, the rest of the band quiets down and lets him have the floor. But one gets the sense that, beneath the goofy exterior, they’re all taking MSR’s emergence equally seriously.

Still growing comfortable with one another, their live shows have revealed them to be a work in progress. But with this enthusiastic, ambitious group of misfits growing before our eyes, it might not be long before they’re living up to the hype. High school may just have ended, but their real education is only beginning.