(Sun files)

The last Indigo Girls album was a milestone, to be sure, marking the folk-rock duo's 20th year of making records together.

But the disc -- called Despite Our Differences -- also represents a slight sea change for the pair, who after two decades together have no interest in being boxed in by convention.

"I don't think this record was a drastic departure," says Emily Saliers, over the phone from Jacksonville, Fla. "But it was time to make a change. To be out of our element was a good thing -- it keeps it interesting. Neither one of us wants to settle into a formula."

Saliers and songwriting partner Amy Ray first hooked up in Georgia in the mid-'80s, during the folk-rock boom that made temporary stars of Tracy Chapman, Suzanne Vega, and 10,000 Maniacs. Though they came from different backgrounds -- Saliers was a graduate of the Joni Mitchell school of singer-songwriting, while Ray was more influenced by punkier acts like The Pretenders -- their debut full-length won them a legion of fans, not to mention a Grammy for the anthemic single Closer To Fine.

Twenty years and countless acclaimed albums later, both women prefer to write what they know.

"I couldn't really write a song like Amy does ... it wouldn't feel natural to me, and I don't think Amy could write the way I do," says Saliers. "But I think we've always felt that our differences were our strength. We write separately, but we arrange together, and whoever writes the song gets veto power."

While their songwriting process may be unchanged, the Indigos were still keen to test themselves.

Since Despite Our Differences was their first disc for Hollywood Records (they'd been with Epic until last year), they decided to leave the familiar confines of Georgia for sunny L.A., where they were paired for the first time with producer Mitchell Froom, renowned for his work with Vega, Los Lobos and Crowded House.

Instead of laying down tracks while isolated in different parts of the studio, much of the album was recorded live, with Saliers and Ray playing together with their band. Saliers says Froom's direction lends a new cohesion to the album, which also benefits from songwriting choices that aren't so overtly political.

"He knows exactly what he's going for, and he never overproduces," Saliers says of Froom. "Whenever we'd ask him to play a keyboard part for us, he'd pick the perfect three notes. He doesn't muck up the songs, he just lets the essence of the songs come through."

Despite Our Differences also features a not-so-surprise cameo from pop-punker Pink, who returns a favour the Indigos did her by guesting on her barbed Dear Mr. President track a few years back.

Saliers says both she and Ray were already fans of Pink when the singer (and budding activist) first contacted them about the collaboration. And they were tickled -- well, pink -- to be able to re-connect.

"She's a very passionate person," says Saliers of Pink, noting the three would talk current events behind Froom's trailer between sessions. "I wouldn't be surprised if she becomes hugely political."

And speaking of politics, do the Indigos ever run afoul -- as Neil Young did the last time he was in town -- of casual fans who don't realize their activism influences pretty much everything they do? "There are some of our songs that are protest songs, but just as many that aren't," says Saliers. "Plus, I think our fans are quite aware of our politics, so there's no griping, no."