"BENEATH" HEADS FOR THE TOP: So you do your song on a big TV show and you see what the response is in the marketplace. Sometimes it works and sometimes it doesn't. And sometimes it really works—as in the case of RCA's Labrinth and guest Emeli Sande performing "Beneath Your Beautiful" on last night's America's Got Talent, which drove the single from #28 to #5 at iTunes today (the soaring duet has sold 300k to date domestically, and close to 3 million worldwide). It's a killer perf, no question, and comes as the song closes in on Top 25 at Pop. (7/25p)