Coming into his new role as one of the principals on “The Voice,” Nick Jonas has recently been spending his time as one of three voices, having successfully reunited with his brothers last year. In between bouts of Season 18 “Voice” work (already taped shows begin airing Feb. 24, and the show turns live in May), he’s scheduled a Jonas Brothers residency in Las Vegas in April, plus work on not just one but two new albums with the bros, who’ll join him as guest coaches on the NBC show.