Let the break-up rumors persist if they must. But with the "Idlewild" soundtrack, Outkast's Andre "3000" Benjamin and Antwan "Big Boi" Patton have proven again that even in tenuous times, they're one of music's most consistently daring groups.

The musical companion piece to their Prohibition-era big- screen film — also debuting this week — "Idlewild" is far from 2000's cohesive "Stankonia." Instead it's a rambling trip through countrified rap, soul, blues and swing with its fair share of hits and misses.

Andre 3000 and Big Boi's increasingly disparate working relationship has been well-reported. Dre stands as the group's eccentric, operating outside of rap conventions and often singing in a passable falsetto.

Meanwhile, Big Boi remains rooted in hip-hop, rhyming with as much clever invention as ever. Rarely do the duo record together. The arrangement worked lovely with each combining solo efforts into one double CD, 2003's Grammy-winning "Speakerboxx/ The Love Below," which sold some 11 million units.

Though "Idlewild" is a singular 25-track affair, each artist's tastes are clearly defined throughout. Of the two songs on which they rhyme together, "Mighty O" is most revealing. The tune, an update of Cab Calloway's "Minnie the Moocher" with tumbling drums and squishy synths, is remarkable for Dre's opening verse. "Eat up whatever rapper/ but I'm tangled in my cord, huh, bored," he rhymes, stating early on a mild disdain for rapping. As the disc continues, it becomes clearer that he'd rather mine his inner Prince.

But the foray into melody that made Dre's best-known smash "Hey Ya!" so ubiquitous it became an unbearable listen, is the same schtick that undermines several of his performances on "Idlewild." The unplugged blues of "Idlewild Blues (Don't Chu Worry 'Bout Me)" is a knee-slapping, guitar-driven good time and his achy croon on "Hollywood Divorce" complements slick cameos from Lil Wayne and Snoop Dogg. However, by disc's end, Dre's vocals sound gimmicky, with the jazz scatting on "Makes No Sense at All" being his biggest offense.

By contrast, Big Boi is rarely out of pocket. On the Dre-produced "Morris Brown," his nimble, triple-time flow buoys the titular college's marching band on the disc's most raucous romp. Elsewhere, he favors reclining grooves whether the subject is baby mama drama ("Peaches"), casual sex ("N2U") or personal reflection ("The Train").

Differences notwithstanding, that's where the magic of Outkast exists — in that balance between Big Boi's accessible ditties and Dre's more experimental excursions. "Idlewild" is the latest proof that one voice without the other would sound much less satisfying.