. . "TWENTY FEET FROM STARDOM, U.S. documentary competition: Morgan Neville, whose 2011 Sundance entry Troubadours centered on superstars such as James Taylor, Carole King, Jackson Browne and Joni Mitchell, now looks at the hired hands backup singers whose oohs and aahs prop up the voices at center stage.What would music be without them?It would be out of tune, Neville said." . . .