The change in My Morning Jacket from their last studio album, the breakthrough "Z," to their latest, "Evil Urges," is not drastic: It's not as if they brought in Timbaland to overhaul their sound or abandoned their scruffy look for more fashionable duds.

Still, much of the buzz surrounding the soulful rock collective's "Evil Urges" has centered on its polished sound and pop potential. The grooves aren't as meandering, the jamming doesn't sound as if it's being pumped out from some neighborhood dive, as it sometimes had. Even frontman and main songwriter Jim James talks about how it sounds "less organic."

"I feel like this is our tightest record in a rhythmic sense," he says. "I feel really happy and proud about it."

All of which has led to speculation that this is the fivesome's attempt to finally make a dent into rock's mainstream: Though the Louisville, Ky.-based group has been beloved by critics and has a feverish fan base that has made them a successful touring band, their biggest-selling CD was 2005's acclaimed "Z" — 216,000, respectable numbers for an indie band but nowhere near close to mainstream.

With the release of "Evil Urges," they've already gotten more exposure. The band recently appeared on "Saturday Night Live," booked its first gig at Radio City Music Hall and plans to close out the year with a New Year's Eve performance at Madison Square Garden. The CD, released this month, sold about 50,000 copies for a top 10 debut on Billboard's Top 200 album chart.

But while their songs may be a bit more refined, and could be more palatable to radio stations, the group — which includes James, guitarist Carl Broemel, bassist Tom Blankenship, drummer Patrick Hallahan and keyboardist Bo Koster — doesn't foresee itself becoming a top-40 band anytime soon, nor is it striving to be.

"It depends on what you think of as the next level, too, because I think we did go to the next level over the last two or three years. It's an incremental thing, which is important to us versus going from however many records to millions and millions of records," says Broemel.

Producer Joe Chiccarelli, who has worked with superstar acts like U2 and Elton John as well as Beck, Rufus Wainright and Tori Amos, says "Evil Urges" is the most "instantly accessible ... groove-oriented batch of songs that the band has done."

The songs, mostly written by James, still have that potent mixture of funk and rock; they bring in more musical elements, and, as Chiccarelli explains, less of a jam-band feel that had defined the band in its early days.

"When I heard the demos and I was just instantly taken by the fact that (James) was trying to say things in a more concise manner, that songs weren't as long or as rambling, they were more focused and to the point," he says.

James, 30, says the band not only wanted to try a different sound, but a more seamless sound as well: He describes the band's drumming as so tight that "sometimes you're maybe confused if it's a real person playing."

For the CD "Z," the band worked with producer John Leckie, whose credits include Radiohead, and recorded the CD in picturesque upstate New York. The result: an album that was a critical triumph and a commercial breakthrough.

But to change things up this time around, My Morning Jacket not only went with another producer but decided to record the CD in Manhattan — in an uncomfortable, cramped studio, as the band describes it, which kept them focused on the job at hand.

The band's growth, in Chiccarelli's eyes, doesn't include plans to become a commercial band with radio-ready hits.

"(The goal is) not to make the songs disposable or slight or pop songs," Chiccarelli says. "I don't think the band is capable of making that. I just don't think it's in them, and I think if that's what they wanted to do they could do that because they are kind of fans of a lot of different music."

Besides, as the band sees it, their career has been gaining momentum with each album — slow, steady, always on the rise.