As leader of San Antonio trio Girl in a Coma, Nina Diaz possesses one of the more stirringly powerful voices in punk rock. Of course, GIAC are more than a punk band, as Diaz's singing frequently crosses over from thunderous, hard-rock workouts to melodically beguiling pop ballads, but she's taking a break from the group to record new material. At past solo shows, idly strumming an acoustic guitar, Diaz has surprised fans with spare, homey versions of Beatles songs like "Something" and, especially, "In My Life," which she transformed into an achingly moving confessional. But tonight she'll be backed by a five-piece electric band and reveal yet another side of herself. Also at Levitt Pavilion MacArthur Park, Friday, July 25.