There’s a rustic mysticism to the music of Cass McCombs. An ethereal vibe. A glittering, twang-tinged opaqueness upon which you can project an entire universe of thought and feeling. Part of that effect is by intent. “I want to leave vast spaces for people to explore their own interpretation because I think that’s even better than what I want, in a way,” the 44-year-old singer-songwriter says in a recent chat over the phone. “Every person has their own interpretation to anything. There are different stages to this…what I want to express isn’t necessarily what the next person feels.” Then there’s the basic reality that McCombs is simply tough to read. “I have…what do you call it? Boundaries,” he says quietly. When asked about how he feels he’s perceived by others, he seemed to recoil at the...