Explosions in the Sky create symphonies out of a drum kit and three guitars. The band (anchored by Rockford native Chris Hrasky on drums) weaves together complex harmonies that sound at once conflicted, hopeful, atmospheric, and — as the name suggests — grand. The ambient post-rockers responsible for the Friday Night Lights soundtrack perform tonight at the Congress Theater alongside former Grandaddy frontman Jason Lytle, whose recent Yours Truly, the Commuter is an album with a languid pace that reflects his California roots. Together, the two acts promise a dreamy, largely wordless show worthy of any orchestra hall.