At age 69, Stephen Stills openly admits that he’s not ashamed to use a few stage tricks to get him through his shows these days. “I once got some sage advice from, of all people, Tony Bennett,” recalled Stills to the packed house at Yoshi’s. “Never be afraid to lower the key or use a teleprompter.” While his voice has become much raspier and his memory impaired enough to recall lyrics without the aid of a screen at foot level, Stephen’s fretwork still shines.