Brothers Ryan and Hays Holladay’s last band, the Epochs, never had trouble attracting the goodwill of bloggers but split amicably in 2008. When the two moved back to this area (they grew up in Northern Virginia), they took the Epochs’ chunky, concise electro-indie with them—it’s the bedrock of their new project Bluebrain, whose songs are a slightly gloomier shade of pop. They also took something else from New York: the participatory boombox performances of iconoclastic composer Phil Kline. The one Bluebrain staged last fall in Dupont Circle sounded like an underwater Madchester rave. For the next, on April 3, they’ll assemble five-minute snippets of music created by Animal Collective’s Geologist and others. It’ll take place beneath the cherry blossoms and promises to be the least prosaic event associated with that dreadful yearly tourist magnet.