These southern-rock road warriors' first studio album since 1994 is surprisingly solid: Returning guitarist Warren Haynes — the best axman to pass through the band since Duane Allman — plays with a steely, tensile power, while youngblood Derek Trucks (drummer Butch Trucks' nephew) counterpoints with mellower, more even-keeled lines. It's an effective restatement of the original chemistry between Duane and ex-guitarist Dickey Betts. The other pieces are in place as well: Gregg Allman's gruff, soulful vocals and cool Hammond organ, Oteil Burbridge's melodic, groove-laden bass work, and the rhythmic sizzle of three percussionists. The freewheeling "Instrumental Illness" lets the guitarists riff, climb and, well, hit the note for another dozen minutes. There's nothing radically new going on here, but the level of engagement is noteworthy.