“We attract people who need that boom and that bap.” That’s more than a line; it’s a legacy. When Diamond District dropped In the Ruff on Mello Music Group in 2009, the gritty drums and grimy raps combined as elementally as hydrogen and oxygen. The D.C. Voltron of Oddisee, yU, and X.O. dusted off and revitalized a sound once consigned to the catacombs -- and thier follow-up is a killer.