Fifteen-year-old blues musician Shannon Curfman proved that age is only a number during her show at the Maintenance Shop Tuesday night. During a nearly two-hour set, Curfman mainly performed songs from her debut record, “Loud Guitars, Big Suspicions.” While Curfman made clear she is quite talented performing original songs like “True Friends” and “I Don’t Make Promises (I Can’t Break)” in the true blues tradition, she wrung more emotion out of work by other artists, blues and otherwise. Curfman’s funk-a-fied cover of Rufus’s “Tell Me Something Good” seemed to particularly win the audience’s approval. Also earning a roar from the crowd was when Curfman promised that she and her musicians would be going into the studio to work on a new record when her tour ends next month. But the sold-out M-Shop would have most likely cheered Curfman had she decided to sing nursery school songs. The true highlight of the show came near the end when Curfman said, “This is the first song I ever learned to play on the guitar.” She then growled her way through the blistering “Malted Milk,” a song by classic, blues artist Robert Johnson. Her band then answered her with a jam session that gave them all a chance to shine. Keyboardist Kevin Murphy was repeatedly featured during the jam. While introducing her encore, Curfman took the time to promote her Web site, www.shannoncurfman.com, revealing to the audience that her mother had been broadcasting the concert via webcam in the process. Curfman went on to say, “This is a song I grew up with, I guess,” as she began a version of John Mellencamp’s “Pink Houses” that caused the audience to erupt and rush to the T-shirt stand once the concert ended. Opening for Curfman was the Des Moines duo Little Mojo. They reached their peak early in the set with a cover of Steve Miller’s “Space Cowboy” that had the audience whooping along. The rest of the set was too reminiscent of Matchbox 20.