Caspian at Felton Music Hall

Experimental post-rock sextet Caspian, active since 2003, stacks multiple guitar and synth textures in billowing layers. At times, their songs take more than seven minutes to fully develop: Sprawling pieces like “Castles High, Marble Bright” from the eponymous 2016 EP build tension with guitar harmonies that weave in and out of dissonance…