Hot Buttered Rum, a souped-up, left-coast string band, is the brainchild of uniquely gifted musicians who weave their love of bluegrass, folk, jazz and soul into a riveting strain of Americana. String bass and five-alarm fiddle merge with guitar, banjo, mandolin, drums and keyboardist frame the voices of its two contrasting writers, fueling a dance party with roots in Appalachia and its branches in California. It’s a sound that’s as tough to describe as it is easy to love.