Chan Marshall (aka Cat Power) has had her on-stage ups and downs. Characterized by unpredictable behavior in front of an audience, Marshall admitted that it’s because she wants everything to be perfect. “The sound, the lights, someone looking at me, maybe the piano’s out of tune, that’s why I stop and start,” she said. “It’s not like I’m trying to torture people.” Whether it’s a perfection complex or what some have labeled stage fright, you truly never know what you’re going to get when it comes to a liver Cat Power show. The singer/songwriter had a tumultuous run in the early 2000s due to a drinking problem, but bounced back and achieved critical success with The Greatest (2007). This Thursday night, celebrating the release of Sun — her ninth studio album — Marshall brings her compellingly minimalist style to Grand Central. Expect the unexpected.