Pop Burger was the original burger joint–cum–party spot, so when partner Kevin O'Connell opened Burger Shoppe in the financial district a couple weeks ago, we were curious to see what would be on the house sound system. Would the soda-fountain motif carry over into personal jukeboxes playing Perry Como, or would top 40 rule the roost? To find out, we settled down with some bone-marrow toasts and a burger made from pork belly. (According to our waitress, no one has gone for the $150 Kobe beef, foie gras, and truffle burger, and we weren’t about to be the first ones to splurge.)