Alt-country love affairs tend to spark with Ryan Adams or Wilco or maybe even Old 97’s. But eventually more sustenance is required, and you find your way to singer-songwriters like Richard Buckner, Jason Molina and Will Johnson. Over the course of 10 albums, Johnson’s primary band, Centro-Matic, has crafted a signature sound: electric, hard-knuckled roots rock. Its latest, Candidate Waltz, is no radical departure, just another quiet addition to a damn fine discography. Polica, a brand-new act out of Minneapolis, favors dark-toned synths, prominent bass and Auto-Tune effects on the female singer’s voice — and, despite this, makes music worth hearing.