Until recently, aficionados of hard rock and hardcore tended to reject each other's favorite sounds for reasons that had more to do with lifestyle than music. Fortunately, however, such nonsensical barriers are breaking down. Take today's KBPI Birthday Bash, which features relatively traditional noisemakers such as HellYeah on the same bill as Horse the Band, a collection of California-based thrash pranksters who wouldn't have gotten a sniff at such a station a few short years ago. "Manateen," a highlight from 2005's The Mechanical Hand, features many of HTB's favorite ingredients; it juxtaposes Erik Engstrom's atmospheric keyboard lines with a stop-and-start sonic assault whipped up by guitarist David Isen and chief shrieker Nathan Winneke. Granted, the players' asymmetrical approach may unsettle listeners who are drawn to songs that remain consistent throughout rather than veering from one extreme to the other. Yet Horse the Band is wild, aggressive and raucous in ways that should appeal to fans on either side of the metal divide. Can't we all just get along?