Big Boi with Killer Mike, Big Meridox, Diversity Higher 8 p.m., Monday, May 20 Rialto Theatre, 318 E. Congress St. $25 advance; $28 day of; all ages 740-1000; rialtotheatre.com Back in 2003, when the white-hot OutKast released dual solo albums—Big Boi’s Speakerboxxx and André 3000’s The Love Below (LaFace/Arista)—something peculiar happened: Big Boi arrived. Speakerboxxx […]