Last week’s opening installments of the latest season of The Voice had more energy than the same week’s finalists-introducing episode of American Idol – and that’s just talking about the judges. Tonight, with votes from the audience and another round of live performances, Idol has all the recipe ingredients – live telecast, so much at stake, viewers finally in control – that could make these last laps around the course very entertaining. And they should. If not now, when? Tonight’s new Thursday-only phase reveals the Top 8, and also makes room for a guest performance by Demi Lovato.