As the golden belt is to the wrestler, so the B.B. King Entertainer of the Year Award is to the blues artist. And Janiva Magness is the 2009 title-holder. By the time this soulful L.A.-based diva with a Memphis musical bloodline reaches Nashville for a rare local appearance, Wednesday’s Blues Music Awards in the Bluff City will have bestowed the title on another. But few can match her blend of onstage sass, soul and sultry tonal authority, to say nothing of the smart song choices and arrangements of her last two albums, What Love Will Do and the new The Devil Is an Angel Too. In a genre too often driven by cliché, Magness pulls songs from outsiders like Buddy and Julie Miller and plays sonic tricks in her mixes, like making upright bass rattle like a garbage truck hitting potholes. Local roots über-songwriter Gary Nicholson opens in the guise of his bluesy alter ego Whitey Johnson.