Those who want to enjoy an ~extremely pleasant~ evening of music and friendship should join Groupmuse, a social-media platform that connects classical musicians with people who want to get tipsy while listening to live classical music in a random person's beautiful apartment.

The concerts are cozy: shoes off, a violin and a cello playing Bach in the living room, Trader Joe's snacks dominating the snack table, amiable young professionals getting wine-drunk with music nerds, and a fuzzy black Lab puppy named Randall sniffing around for cuddles.

Or at least that was my experience at a Groupmuse hosted by Kelly Elder, a 28-year-old attorney who invited 15 people and two musicians into her gorgeous peach-brick corner apartment in Eastlake last Saturday.

I selected Elder's event because it was called "Classical Caturday," since I like cats and puns.

The cat, it turned out, was a lie. Elder told me Lucy, a reportedly grayscale-colored feline, was in hiding. She doesn't do well with lots of people. But I took solace in a teddy bear-shaped ottoman (with ears!) in the living room and in the pretty cobalt sky slowly darkening over Lake Union, which I could see out the windows. When another guest showed up with the puppy, the world became fresh and new and alive again.

Most of the guests knew Elder or her boyfriend, Tyler, from college. Elder told me there are three kinds of people involved in any Groupmuse: hosts, guests, and musicians. Hosts control how many (and which kind of) people to invite to the party. Since this was her first time hosting, she went with a ratio of two-thirds friends to one-third people from the Groupmuse community, i.e., strangers. She screened for weirdos by lightly Facebook stalking them, though everyone seemed cool. Guests pick the event they want to attend and pay $3 to reserve a space.

A variety of musicians participate: classical guitarists, quartets, two-piece string sets. One guy said he'd been to a Groupmuse where an early-music purist rolled up to the apartment with his own harpsichord. Most musicians are professionals or grad students who use the nights to try out new material, practice for upcoming gigs, and/or make spare cash.

Our night featured violinist Jason Hershey and cellist Peter Ellis, who have been playing together since they met in middle school. They performed an hour-long set that mixed baroque with modern: eight pieces from Reinhold Glière, Arcangelo Corelli's "La Folia," and a few numbers by Michele Mascitti, who Hershey said he'd recently discovered on Spotify.

During the day, Hershey works in finance, but he plays in community orchestras around town, too. He's been a member of the Boston-based website since it branched out to Seattle about three years ago, and says the community has significantly grown in the last year or so.

Ellis is a full-time musician and cello teacher. He plays Bach at farmers markets and generally does a lot of street performances.

The only tense moment the whole evening came when Hershey busted a string. Ellis covered for him with a little music.

"Uhh, it's Bach's birthday!" he said. "Happy birthday, Herr Bach. To honor him, perhaps the 'Sarabande,' the slow movement from his first suite." He played the piece beautifully, his ponytail cascading over his right shoulder.

The music was entrancing. Chamber music sounds warmer and more intimate when it's actually being played in someone's chamber.

Audience members chatted with the musicians between songs. "Was that the Mascitti?" someone asked. "It was," Ellis answered.

During a 15-minute intermission, Tyler passed around a lunch box. Suggested donation for the musicians is $10. You can bring cash or pay on the Groupmuse app.

As it was a Saturday, people hung around after the show proper ended. To entertain the wine-sloshed stragglers, Ellis played his street Bach, the Star Wars theme, and a couple other great pieces he stores in his head.

Elder said she'd definitely host again. "Next time, I'll invite more strangers," she said.