INDIGO GIRLS Twenty-five years into their career, the Indigo Girls — Amy Ray and Emily Saliers — have settled into a comfortable folk-rock niche. And that’s how their music sounds — comfortable. It’s been a long time since the two released anything that came close to capturing the visceral energy of their self-titled debut or 1992’s Rites of Passage. But the Girls’ vocal powers remain intact, and their lyrics continue to probe the depths of the human experience. With the backing of a full band, Ray and Saliers are sure to put on a good show, but at this point, Indigo Girls performances might as well be billed “For Serious Fans Only.” With The Shadowboxers. $39.50-$59.50. Oct. 18, 7:30 p.m. McGlohon Theater, 345 N. College St. 704-372-1000.