Hardcore and classic rock used to be musical opposites. But it turns out that they can harmoniously co-exist in the same song. You can credit the unifying power of the almighty riff, which Kingdom of Sorrow — featuring Jamey Jasta, frontman for metalcore standard-bearer Hatebreed, and Kirk Windstein, guitarist for stoner-rawk all-stars Down — dutifully applies on its self-titled debut. Not so surprisingly, the album sounds as if it were made by the guy from Down playing guitar in Hatebreed. Drummer Derek Kerswill (who's done time in Unearth and Seemless) and bassist Matthew Brunson make up this side project's pile-driver rhythm section, and they pull Kingdom of Sorrow into a sweaty mosh pit in "Led Into Demise" and "Piece It All Back Together." Even longtime fans will find Windstein's riffing here more consistent than what he played on Down's recent Over the Under. The smoke-trail dirge "Grieve a Lifetime" certainly deserved a spot on that album. Handed that gem, Jasta gives his most impassioned performance ever, finally pushing his wounded-bear roar into an emotional range that goes far beyond his usual pissed-off indomitability.