On their way to the bathroom on a flight to Seattle, the Black Keys spotted the lead singer from Train in first class. "He looked like a 40-year-old toddler," drummer Patrick Carney recalls. Should the plane crash, they realized, their names could be uttered in the same breath for the rest of time. From his front porch in Akron, Ohio, Carney laughs. "Our non-existent legacy would be gone forever."

The Black Keys may be one of few no-nonsense bands in a time when every musician feigns indifference -- and they don't take kindly to poseurs. "When you play those big festivals, you're surrounded by bands like the Bravery -- new bands that are mediocre but wear lots of makeup and have egos the size of Manhattan." For two regular guys, the endlessly-posturing indie scene can be tiresome. "Most good bands have no ... type of ego -- they're just decent dudes."

Their seeming authenticity is what has drawn in critics and fans alike. The Keys are a two-man blues-rock affair, made up of hometown friends Carney and Dan Auerbach(guitar, vocals). Their sound -- often described as "dirty" and "raw" -- is earnest, classic guitar rock filtered through lo-fi production. The most notable feature is Auerbach's blues-informed yelp, strikingly at odds with his slight, Midwestern frame. It is Carney's indie-rock influences, though, that may help explain what keeps their material fresh: "To me, Robert Plant and Stephen Malkmus are held on the same pedestal." These modern sensibilities, subtle though they are on record, keep the Keys from being pigeonholed as a one-trick pony.

With the release of Rubber Factory in 2004, they're also learning to cope with mounting popularity. The album is their third critically-hailed effort in as many years and has brought with it many of the perks of widespread national attention: bigger venues, the aforementioned festivals and a hilarious, David Cross-directed music video for their single, "10 A.M. Automatic."

The Keys are also grappling with the downsides of success. They've already had to deal with record label disputes, and more industry issues are on the horizon. "It's the first time we have to make decisions that are uncomfortable, you know, business decisions ... whether or not to let Nissan use a song." It's a jarring adjustment for a band that once recorded an album for over 12 straight hours in Carney's basement.

Though the Keys have been taking some needed time off in recent months, Dan and Patrick aren't laying low for long. In February, they will release an EP of covers by blues legend Junior Kimbroug. "I think it's our best stuff. It's really dark. It's really fucking weird." They've also begun recording the follow-up to Rubber Factory at home in Akron. The new LP, tentatively slated for a summer 2006 release date, they describe as "a heavier record than we've ever made."

Some critics have pointed to their two-man lineup as ultimately limiting. For now at least, the band has no interest in messing with the existing dynamic, which Carney sees as their real inspiration. "Everything is warping and moving. It's like the two of us are locked into playing together." If that sounds like an acid trip, Carney swears: they're not into hard drugs.

The dynamic reportedly comes across especially well onstage. Carney agrees. "Expect the most awesome concert probably you and your parents have ever seen.

"Probably."

The Black Keys will play at the Theater of Living Arts (334 South St.) tomorrow at 9 p.m.