Despite powerhouse vocal workouts like “Rain,” PATTY GRIFFIN ’s last studio effort, 1000 Kisses, felt like a retreat to a safer place. This was not expected: The Bostonite-turned-Austinite, an uncompromising singer and writer, didn’t achieve commercial success by taking baby steps. IMPOSSIBLE DREAM ( ATO) finds surer footing artistically if not emotionally. Griffin pours herself into the soul-blues of “Standing” and the kickoff “Love Throws a Line,” a love-or-else tune that shines some rays of optimism. Otherwise, the lights stay low. There’s a beaten-down resignation to these songs that fans of, say, Springsteen’s Nebraska will appreciate. Dream is no Nebraska, but Griffin’s work finds a similar pain and poignancy.