Listen to both versions of "Stoop So Low," off Gov't Mule's new double album "Shout!"

Two songs inspired the unique direction of Gov't Mule's new album, "Shout!"

The set, due out Sept. 24, features two separate discs, one featuring the original versions of the 11 songs as written and performed by the Warren Haynes-led quartet, the other featuring the same songs with guest vocalists, an all-star cadre that includes Dave Matthews, Steve Winwood, Elvis Costello, Ben Harper, Grace Potter, My Morning Jacket's Jim James and others. But Haynes assures Billboard, he and the band "didn't start out with that intention."

"We just started making a Gov't Mule record," Haynes explains, "and there was one song and then two songs and then three song that we felt like were just so different that the idea of bringing a guest came up gradually."

Gov't Mule started by bringing in Toots Hibbert to sing on "Scared to Live," then went to Dr. John for the track "Stoop So Low" (hear it exclusively above and check out the Doctor-less version below).

"That was in honor of Sly & the Family Stone's 'Fresh,' the 40th anniversary," Haynes says. "When I listened back to my vocal performance, it started reminding me more of Dr. John, and we were about to be on tour with Dr. John and I thought, 'Well, maybe I should ask Mac to sing the low verses or something."

Dr. John dove whole-hog into the tune, which, like most of the songs on the album, differs significantly from the Gov't Mule treatment.

"In almost every case, we specifically, intentionally changed the arrangement -- sometimes before the sang the song and sometimes after they sang the song. We were consciously not wanting to offer the same arrangement twice," Haynes says. "I think everybody delivered above and beyond what was expected, but that's what you would expect of these people. These are great singers that I genuinely love and respect, and so it's only appropriate that each of them would take the song somewhere that I would never think of."

But Haynes says he isn't concerned that the high-profile guests will eclipse Gov't Mule's renditions of the songs.

"I think the positives far outweigh any potential negatives in that regard," he says, "especially since the biggest part of the life of this album is going to be next year when we celebrate our 20th year. I think ('Shout!') kind of goes hand in hand with celebrating Gov't Mule, and I also feel with today's mode of the music business you have to constantly reinvent the concept of putting out a new release and stumbling upon something that has never been done before. I think what we did here is hopefully going to garner some attention beyond what we'd normally get."

Haynes says Gov't Mule is "just starting to have the dialogue" about how to commemorate the 20th anniversary.

"I'm sure it will involve collaborating with a lot of our friends and colleagues, trying to do at least a handful of, if not more, special shows and trying to release some cool archival stuff and boxed sets and things like that." Haynes says the latter could include an all-instrumental live album Gov't Mule made with John Scofield during during the 90s and possibly anniversary editions of individual albums with previously unreleased bonus tracks.

Gov't Mule hits the road to start promoting "Shout!" on Sept. 13 at the Harvest Jazz & Blues Festival in New Brunswick and has dates booked into early November. Haynes just finished his annual summer run with the Allman Brothers Band, and while he acknowledges the group continues to dial down its touring schedule he says a new album is "maybe even a better possibility than it was a year ago. We're not ready to go in any time soon, but we are a lot closer than we were. We need to delegate the time to know that we have the material. I think everybody kind of unspokenly agrees that if we are going to make a record it's got to be as good or better than (2003's) 'Hittin' The Note.' There's no reason to do what I think we would all look at as the last Allman Brothers record unless it's gong to be on par as the last one before it. and I think we can easily do that if we delegated the time and the energy to make that happen. We don't have an album's worth of material right now, but we are getting closer to that point."