There are a couple of shows at the Pageant this week that deserve your attention (not to mention attendance). First off: On Friday, catch the Loop Underground show, featuring U. City rappers who aren't about to release an R&B album to appease their older fans. Older fans, however, may prefer to show up Sunday for the Oliver Sain tribute being sponsored by KDHX (FM 88.1). Featuring Little Milton Campbell and Fontella Bass, among others, it ought to be a searing night of soul music.