It's difficult to imagine British six-piece The Go! Team sounding like anything other than an aggressively cheerful indie-pop pep squad: When a band traffics in such a distinctive sound, sometimes the best—and most challenging—thing it can do is maintain that momentum. For the most part, the new Proof Of Youth is a willing, successful continuation of 2005's frenetic Thunder, Lightning, Strike. "Grip Like A Vice" is an air-raid siren of an opener, with female MC Ninja dropping double-dutch rhymes over Ian Parton's mishmash of brass, feedback, and handclaps; "Titanic Vandalism" and "Flashlight Fight" are similarly explosive. The disc features cleaner production, more instrumentation, and fewer samples (plus a couple of noteworthy collaborators in Chuck D and Bonde Do Role's Marina), but that extra polish comes at the expense of Thunder's exhilarating sense of barely contained madness. Whereas that album has enough raw energy to sustain initial adrenaline blasts, many of the songs on Proof ebb after the one-minute mark, and the endearing funk-chant-clap equation threatens to become monotonous. Proof still offers plenty of pep, but without its predecessor's ragtag charisma.