Music fans wanting to experience the diversity of South Central Texas’ music scene are in for a treat this week. On Wednesday, UTSA will turn its underground tunnel system into a free, day-long showcase for local and regional music, and on Saturday, Austin-based psych rockers Megafauna will pair with two of San Antonio’s most original acts — HoneyBunny, and Powered Wig Machine — for an adventurous bill at the Paper Tiger.