Over time, Mimi Parker and Alan Sparhawk have built up a songbook that involves them subtracting, piece by piece, whatever a song doesn’t need. At the end of the day, all it really needs is their singing, but here, they still have a band with drumming and guitars. The pace is as slow as ever, and they are still in the same family as Codeine and Slint and other bands that played rock extremely slowly, all of it descended from Neil Young. Low, though, are something else. Their music is sacred, a new kind of hymn that brings in pieces of modern music, more out of curiosity than anything.