There’s no more persuasive evidence that we’re in the twilight of the “Rock Star” than its appropriation by the tech sector to mean little more than someone with a penchant for wearing black and an inflated self-regard. But there are still a few true rock stars still plying their craft, including Bruce Springsteen who, in his 40th year touring as a major-label artist, is criss-crossing the US in support Wrecking Ball, his latest record, album, melange of mp3 tracks.