Adventures in hi-fi

''Indie" is one of those words that's changed, dangerously, over time. It began literally enough as shorthand for independent musicians and record companies that were operating outside the major-label system. But it became imbued with ideology, a buzzword for the hip-kids club whose members wear their integrity and autonomy and anticommercialism like badges of honor.

In the prickly battle of art vs. commerce, LA pop group Rilo Kiley is facing the quintessential indie dilemma: Can a band that's come up through the low-budget ranks expand its fan base without sacrificing its outsider ideals?

''I personally struggle with it every day," says Rilo Kiley frontwoman Jenny Lewis, who cofounded the band in 1998 with guitarist Blake Sennett. ''We tread carefully. I find myself politely saying no to things that don't feel natural or within our frame of reference. People make such a big deal about indie vs. major. But if you're making the same music, what's the fuss about reaching more people?"

Rilo Kiley, which also includes drummer Jason Boesel and bassist Pierre de Reeder, moved to the dark side last year when -- on the eve of delivering ''More Adventurous," its third album -- the band cut ties with the Omaha-based Saddle Creek label. Founded by indie-rock poster child Conor Oberst of Bright Eyes and home to an elite community of proud fringe dwellers that includes the Faint, Azure Ray, and Cursive, Saddle Creek oozes indie virtues and incorruptibility -- to the point where the band members felt their growth would be constricted by the label's commitment to remain outside the mainstream. Rilo Kiley, which plays at Avalon on Sunday, is the first band to leave Saddle Creek in its 12-year history.

''There were some differences specifically with regard to radio stuff," Lewis says. ''We wanted the opportunity to explore those things, and Saddle Creek was uncomfortable with that. I have nothing but respect for them; they've created a tightknit mini-empire based on a philosophy, and that's great. But for us all the principles didn't apply."

''More Adventurous" is technically out on the band's own Brute/Beaute label, but Warner Bros. has been responsible for the distribution of the album. It's the WB logo on the press releases, company cash financing the band's video, and well-connected staffers pushing songs to radio and television -- Rilo Kiley's song ''Science vs. Romance" was featured, and the band was name-checked by a character, in an episode of ''Gilmore Girls" last fall.

Lewis confirms that Rilo Kiley is poised to sign a new contract with Warner, which will officially make the band part of the major label's roster. She was informed earlier this week that her band will be opening a string of shows for Coldplay this summer.

''It feels," Lewis says, simply and with no shame, ''like a natural progression."

Indeed, ''More Adventurous" is lusher and cleaner than either of Rilo Kiley's previous projects: the infectiously lo-fi 2001 debut, ''Take Offs & Landings," and the following year's ''The Execution of All Things," a quirky country-rock collection embellished with horns, strings, and an Oberst-led ''boy choir." The new disc -- released last fall -- is smart and charming, swirling and robust, a hook-filled pop valentine with a heart of darkness. The album's title, and the title song, isn't about the band's musical direction so much as Lewis's outlook in life.

''Having not had the most positive experiences, it's really easy to close yourself off from positive things," she says. ''It's a personal statement about relationships, and allowing yourself to love again. ['I read that with every broken heart we should become more adventurous,' goes the key line.] It was important to say it in the song because maybe after singing it a million times it becomes the truth."

Without prying, it's hard to know exactly which relationships Lewis is alluding to. She and Sennett became lovers after forming Rilo Kiley, and although the romance fell apart after two years, they were both determined to keep the band together.

''We became friends because of the music, and the romantic stuff was a product of that, and once we were able to get over the initial shock [of breaking up] I think we really wanted what's best for the other. We care so deeply for each other. But we come from different places."

Different as they may be, Lewis and Sennett also have a strangely linked history -- as child actors. He was a regular on ''Boy Meets World," ''Family Ties," and ''3rd Rock From the Sun." Lewis was born in Las Vegas and soon after moving to Los Angeles became the sole breadwinner in her family, appearing in countless films and television shows, among them ''Growing Pains" and ''Troop Beverly Hills."

She reflects on that part of her life with mixed feelings.

''There's a certain sacrifice one makes when they're a child and also the responsible financial person," says Lewis. ''At the same time it was good training in terms of having a work ethic, which I think I bring to the band." To the suggestion that their common experiences in Hollywood must have been a bond between Sennett and Lewis, she says that ''it was more feeling embarrassed at what we had done. I didn't get the parts I wanted. I was unfulfilled at 12."

Which may be why Lewis and Sennett are applying themselves with gusto -- and unabashed ambition -- to their new roles in pop music. In addition to taking the major-label plunge, most of the members of Rilo Kiley are busy outside the band: Sennett in his solo side project the Elected, Lewis recording and touring with the Postal Service, Boesel backing Bright Eyes. Lewis has just wrapped up her first solo album, which she describes as sparse and gospel-flavored. It was produced -- like the last two Rilo Kiley albums -- by Saddle Creek mainstay Mike Mogis. Oberst's Team Love label will release the disc later this year.

Clearly, Rilo Kiley's connection to its roots in the fiercely independent Omaha scene is alive and well.

''Even though we're not on the label, we're all so tied," Lewis says. ''Nobody wants anybody to be unhappy. And nothing's really changed. I don't even know if we've sold more records. I don't think so. But if we hadn't left, we'd still be wondering."

Joan Anderman can be reached at anderman@globe.com.