If you haven’t checked in with Germantown-bred foursome Surgeon in a few years, you’re in for a surprise. In 2008, the band had a Steve Albini-produced, self-released record called Angry Guest that balanced distortion pedal aggression and rock melody; its murky, moody single “Walking Fire” was in regular rotation over in the HD/Internet radio wing of WXPN. Since then, Surgeon has remained a fixture on Philadelphia’s rock club scene, but massively pushed the boundaries of its sound to be somehow heavier, and yet more tuneful. On its latest batch of songs, shown off in the band’s recent Key Studio Session, we hear Sean Boltron delivering insanely catchy rock choruses on “Watching You” and “Animals,” while drummer Dave Latimer pounds his kit and lead guitarist Lydia Giordano positively shreds. Check out her dueling intro with rhythm guitarist Chris Wilson on the brand new, never-before-recorded cut, “Greed”—it’s totally Yngwie. Tune in to XPN2 tomorrow night for the Key Studio Sessions Hour to hear members of the band talk about their creative process and a trio of upcoming appearances on their calendar: Oct. 13 at The Legendary Dobbs, Oct. 28 at The Fire and—for metal fans in the burbs—Oct. 29 at Tom N’ Jerry’s in Milmont Park.