While it might not have a “pop” immediacy, Alpha Hopper’s corrosive sound is still bright and accessible, poking at our spongy brains with a pointy stick and a mischievous smile. Let Heaven and Nature Sing II, their first album in nearly five years, is oddly mesmerizing, picking apart blistering riffs and pounding drums, constructing a rampant onslaught of boundless energy.