Jason Aldean is a young, earring-wearing hat act who plays the Nashville game the way it’s always been played — order up 12 or so songs from the best songwriters money can buy and sing the hell out of them. But he leans on guitar instead of fiddle or pedal steel and his second CD, which is loaded with better-than-average material, could almost be seen as a Southern-rock record. On the terrific single, “Johnny Cash,” he flips off the boss and heads out to get his girl in the first 30 seconds. The title track has an engaging modern-rock feel, and “Back in This Cigarette” is just cool. There are some clunkers (his debut had better ballads), and though Relentless is almost certain to fly under the radar of the national music press, it will reward anyone who seeks it out.