After a deservedly thunderous ovation, the Who returned for a mostly acoustic encore of "Won't Get Fooled Again," "Behind Blue Eyes" and "Who Are You." It felt oddly unnecessary and was certainly less urgent and dramatic than what had come before. In contrast, "Quadrophenia" sounded Who-ish, looked Who-ish and was most definitely Who-ish. The codgers are all right. CAPTION: Just like old times: Lead singer Roger Daltrey belted out a tune last night at USAir Arena as the Who revisited its 1973 theater piece, "Quadrophenia."