Where is the excitement in a Josh Groban album? Is it in the crystal-clear way he belts out his high notes? Or is it in the way he gets co-signs from everyone from Rick Rubin to Herbie Hancock? There’s no doubt that the operatic pop singer is one of today’s great vocal talents, and he has proved he can be very funny on social media and talk shows. But his music could desperately use some of that spark: Groban’s seventh LP is a set of technically proficient covers of musical-theater tunes that falls flat emotionally. The high points are duets with Kelly Clarkson (“All I Ask of You”) and Audra McDonald (“If I Loved You”) that at least hint that such a well-oiled machine can feel.