We’ve been talking up the music of USM professor and composer Dan Sonenberg since his indie-rock project, Lovers of Fiction, released its excellent EP last summer, but the big event is this month: the world premiere of The Summer King, Sonenberg’s opera about the struggles and triumphs of gate-crashing Negro League baseball player Josh Gibson. It’s at Merrill Auditorium (20 Myrtle St., Portland) at 7:30 p.m. Tix: $35-$42 ($10 students). 842-0800. portlandovations.org.