TRACE ADKINS Cowboy’s Back in Town [Show Dog/Universal] Trace Adkins’ new album begins with a punchline about the wah-wah guitar lines that once dominated porn soundtracks (“Brown Chicken Brown Cow”) and ends with a hillbilly brawl (“Whoop a Man’s Ass”). In between, the rest of this underwhelming set might make you forget the fact that Adkins, with his profound baritone, is one of modern country music’s most powerful voices. When...