Nashville Star’s first-season runner-up john Arthur martinez (the eccentric capitalization scheme is a nod to poetry hero e.e. cummings) didn’t immediately parlay his TV notoriety into mainstream success, but he has spent the ensuing six years building both a solid catalog and a loyal following centered in his native Texas. Purgatory Road finds john sounding a little moodier than usual, as signaled by the keening steel guitar that kicks off opening cut “Utopia.” Hopefully this will be the moment that the national audience john briefly held six years ago comes back around to a remarkably consistent talent.