SERIES PREMIERE: This new music competition series could be an instant hit, a slow roll, or an equally instant flop. Like American Idol and The Voice, it has aspiring talents performing in front of a panel of attention-stealing judges. The slight twist, this time around, is that the contestants are songwriters, not merely singers – so the songs they sing are their own, pitched to the week’s guest artist. For the premiere, that guest artist is John Legend, fresh (or relatively fresh) off his stint as judge on NBC’s The Voice, shows up to give an opening-night boost to this new show, and the songwriters pitch songs they hope he will not only like, but record. And there’s another Voice connection, too: This show comes from veteran Voice judge Adam Levine. The big question with this new summer TV competition show, of course, is whether viewers will tune in and give the program momentum. If so, it can be a successful franchise, like this new show’s NBC lead-in, America’s Got Talent. If not, it’ll vanish, like The Great American Band. Never heard of it? My point exactly.