Kix Brooks says it gets harder to be Brooks & Dunn with every album.

Although that may sound like some worn-out comic cliche, that simple realization cuts to the core in explaining what drives Brooks and Ronnie Dunn to keep pushing on together when they've accomplished virtually everything a country act could hope to achieve.

This is, after all, the duo who have sold 27 million records, reeled off some two-dozen hit singles and owns shelves full of country music awards, including multiple entertainer of the year honors.

"When we get to the point that all that we have left is our hits and fairs and festivals to play in the summertime, we won't be doing this anymore," Brooks said. "We have no desire to rest on our laurels and play an oldies show or whatever. If we can't bring something new and exciting and challenge ourselves to do something that's special … there's not going to be a Brooks & Dunn."

And Brooks said the longer he and Dunn stay together, the bigger the challenge becomes to satisfy their artistic goals.

"We have to work so much harder than we did back when because there was so much new ground to be broken for us back then," he said. "I try not be redundant, but it's more of a challenge every CD you put out to come up with something different, and especially when your bread and butter is good-timing honky-tonk music. It's like how do you retell that story to where people go 'Gosh, they did it again. That's different. That's what we love about them, but that's different.' And when you pull it off, it's one of the most gratifying things there is."

The realization that Brooks & Dunn needed to embrace the idea of tackling new creative challenges became especially clear after the duo's 1999 CD, "Tightrope."

Even before that CD, Dunn had lobbied to part ways with producer Don Cook and bring in a new producer and new musicians to bring fresh energy to the studio process. Brooks balked at the suggestion. He had started writing songs with Cook years before he and Dunn were brought together as a recording act in 1990 by former Arista Records President Tim Dubois. He was torn by his loyalty to Cook.

So the duo compromised. Brooks had Cook produce his tracks for "Tight Rope," while Dunn worked with producer Byron Gallimore.

The move didn't work. Critics felt the songs and performances on "Tight Rope" were lackluster, and sales backed up that opinion. After seeing six previous albums routinely sell in the millions, "Tight Rope" struggled to reach the 500,000 mark needed to be certified a gold album.

The failure of "Tight Rope" forced Brooks and Dunn to take a hard look at whether they even had a future as a duo, and if so, what artistic goals should they pursue. Facing those questions, Brooks said, strengthened their partnership.

"It did open a new level of honesty," he said. "There were very frank discussions. It's like either we're going to work together or let's not work together at all. Let's blow it off. If we're going to be a duo let's be one or let's go the solo route. You can't have it both ways. I think we were trying to walk that line back then, and it wasn't fun and it wasn't successful. There wasn't any reason to continue on that course. That was just a death spiral there."

Recommitted to their partnership and their music, Brooks & Dunn teamed with a new producer, Mark Wright, to make "Steers & Stripes." The 2001 CD restored the duo's commercial momentum, yielding three No. 1 singles -- "There Ain't Nothing 'Bout You," "Only in America" and "The Long Goodbye."

With "Steers & Stripes," Brooks and Dunn didn't reinvent their music so much as they refined and rejuvenated the mix of high-charged rock-edged country (think of hits such as "Boot Scootin' Boogie" or "Hard Workin Man") and full-bodied balladry that had been their signature from Day One.

But the next CD, the 2003 release "Red Dirt Road," pushed the envelope further. Working again with Wright, the duo pursued a rootsier sound and also brought out a soul music influence that had never been fully featured in their music. It was the most refreshing CD in years for Brooks & Dunn and a record Brooks felt really represented a creative resurgence for the duo.

"'Steers & Stripes' had a lot of production value," Brooks said. "I think we went down that (rootsier) road a little bit with 'There's Nothing About You' and whatever. But there's still a lot (of polish) on that record, I could feel us starting to wake up on 'Steers & Stripes.' "

The latest Brooks & Dunn CD, "Hillbilly Deluxe," which was released in September 2005, continues to pursue the more stripped down and earthy sound of "Red Dirt Road," while still retaining the rocking attitude that has been the Brooks & Dunn signature from the beginning.

Though "Hillbilly Deluxe" builds on the direction first charted on "Red Dirt Road," it features one major departure from that album. For the new CD, Brooks & Dunn partnered with one of country's most respected producers, Tony Brown, whose past credits have included albums by everyone from Steve Earle and Nanci Griffith to George Strait and Reba McEntire.

Brooks praised Brown for his ability to spot and correct subtle weaknesses in some of the songs as they were recorded. He also said Brown showed considerable restraint in not overproducing tracks, noting that Brown even chose to put demo recordings of a few tunes on "Hillbilly Deluxe" because he thought the spark in the original recordings couldn't be surpassed if the songs were re-recorded in a full studio environment.

"I think we're more interested in leaving the blemishes on there and having that raw attitude and that vibe and that feel in the music that's really what brought us to music and the recordings that we really love," Brooks said. "Especially with honky-tonk music, I think that rough attitude is what makes it fun, makes you gravitate to it."