BY DAN DELUCA INQUIRER MUSIC CRITIC On a recent shopping Saturday, I found myself in a suburban Banana Republic, a Pine Street photo gallery, and a chichi Center City cafe. I bring this up not merely to establish my credentials as an effete poser, but because Feist was playing in all three places. That’s Leslie Feist, the Canadian indie-pop singer who goes by her last name when making her own music. (She’s also a sometime member of the Toronto collective Broken Social Scene, and used to perform along with electro-rapper Peaches under the name Bitch Lap Lap and sing with the frosty Norwegian duo Kings of Convenience.) Let It Die, Feist’s excellent 2005 album, scored an adult alternative hit with the shimmying “Mushaboom.” But although it was declared a personal favorite by tastemakers such as OutKast’s Andre 3000, the CD had modest U.S. sales of 100,000. (Most of those buyers apparently were baristas and shopkeepers.) MORE