For Sam Bodkin, founder of Groupmuse—a network connecting classical musicians with millennial audiences through BYOB house parties turned chamber concerts—Beethoven’s Große Fuge was a gateway drug. “My first year of college, I was sitting in the basement of one of my best friends,” a cellist who gave an impromptu performance, Bodkin recalls. “It was truly one of the formative moments of my life.” Bodkin started raiding the Newton Free Library’s classical section; soon he was hooked. “I decided I was going to devote my life to figuring out how to bring my generation close to classical music, because a sort of unfortunate corollary to this wonderful personal discovery was the realization that my generation didn’t know sherbet from Schubert.”

The Groupmuse concept started marinating after Bodkin met New England Conservatory students who threw house-party concerts in Allston. “It was very much a college party—drinking, socializing, partying—but it was tied together by truly great young musicians playing their hearts out.” Coupling that experience with memories of Couchsurfing across Europe, he hosted the first Groupmuse in January of 2013. Now four to five Groupmuses gather every week. After each, a bowl for musician donations is passed around, as is a clipboard so attendees can volunteer to host a party for their own friends and members who’ve RSVP’d through the Groupmuse website. “We are so overwhelmed by how well this has been working in getting young people to come to classical music every single week.”

Bodkin thinks Boston’s character has much to do with the rapid growth. “It’s a small city, but we have all these world-class cultural institutions,” he says. “You have this preposterous concentration of musical talent.” But starting this month, Groupmuse is expanding, with parties planned for Austin, Philadelphia, San Francisco and New York. Bodkin’s also developing a revenue model. “The problem is, of course, that 20-somethings are the most hilariously broke demographic,” he says. “But we do know that there are probably more affluent middle-agers that also want intimate experiences with art that’s so close—just a foot away. And they don’t necessarily want strangers coming into their homes and getting tipsy.” The plan is to curate private performances for clients who control the guest lists.

But Bodkin’s mission remains making classical accessible for young audiences—as reinforced by a recent comment from a first-timer that was music to his ears. “He said, ‘I don’t think I’ve been in a room where so few people were on their cellphones for such a long time.’ That made me so happy.”