Throughout the fighting, Armand Diangienda’s music never stopped. Near-constant war and repressive regimes have defined his native Democratic Republic of the Congo. But for 21 years, he’s realized his dream of transforming “church music” into a popular art form. The conductor’s 80 musicians and 105 singers — all volunteers who’ve improvised with objects like minibus wheel rims for chimes — are the toast of Kinshasa, playing classical music inflected with tribal rhythms. They’re now charging for concerts and raising funds for a music school to help ensure that the beat goes on.