Black “concert dress” isn’t a requirement anymore.

The implications that accompanied stone-silent auditoriums, snub-nosed culturists and black-tie regulations have faded into the era they were born in, and in their place, a new generation of chamber musicians has arrived.

As the result of a progressive classical music culture, what was known to Beethoven and Mozart as traditional chamber music has expanded to the point of redefinition.

“It’s pretty clear that the standard classical music world has been really looking for a new kind of outlet for a few years now,” says Carla Kihlstedt, violinist for the edgy, San Francisco-based Tin Hat Trio. “I think the classical world is trying to reach out into world beyond classical.”

To appeal to these baby boomers, the standard concert black is being replaced by theatrical costumes; European-carved string instruments are being substituted by electric concoctions, similar to rock ‘n’ roll instruments; and impeccably timed glissandos are being faked with spur-of-the-moment slurs and slides.

Role models like the spiky haired Kronos Quartet, the stir-crazy Soldier Quartet and the jazzed-out Turtle Island Quartet have pushed their way through the land of string stereotypes, breaking molds and shocking the chamber music world in the process.

Years after the inception of these pioneering groups or “bands,” as some would prefer to be called, new conservatory classes are still turning their heads in curiosity. However, despite the increasing interest among students, most traditional conservatory professors shake their heads in disgust.

“I had to find [this style of violin playing] against the wishes of all my teachers,” Kihlstedt says. “The people who teach in conservatories’ reality is pretty narrow. What they know is classical violin, and it was really up to me to find other things.”

When Kihlstedt was attending Oberlin Conservatory, she joined a secret group known as the Oberlin Avant Guarde, which provided a non-classical outlet for the technically trained classical students.

“It was basically an excuse to get together and explore different types of improvisation,” Kihlstedt says. “That was the most formal my improv training got.”

After Kihlstedt finished her schooling at Oberlin Conservatory and Peabody Conservatory, she moved to Oakland, Calif., where she hooked up with long-time music contact and rock guitarist Mark Orton.

“When I moved out here, it was the first time in my life when no one knew I was a classical violinist,” she says.

It wasn’t long before Kihlstedt, Orton and accordion player Rob Burger started jamming together, exploring the trails paved by their predecessors.

The style they came up with, which blends tango, bluegrass, contemporary classical and Eastern European folk music, soon caught the attention of San Francisco’s adventuresome music scene, prompting the group to cut their first album last February.

As the Tin Hat Trio continues to exploit the diverse musical tastes and backgrounds of its personnel, they plan to not only keep up with the ever-evolving chamber music trends, but also clear some new ground.

Kihlstedt admits it’s hard to tell what this formerly mapped-out genre of chamber music will lead the group to explore. As more chamber groups start to incorporate dancing, drum accompaniment and samplers into their concerts, the line is becoming less and less visible.

“I think that ‘line’ changes depending on whose perspective you’re speaking from,” Kihlstedt says. “I’m sure there’s people who are more traditional who would say, ‘That’s not chamber music.’

“But chamber music means ‘small group’ – music you would literally play in a salon,” Kihlstedt says. “In order to keep music alive, it needs to metamorphose and keep up with the times.”