THE HAPPY HOLLOWS Amethyst thehappyhollows.blogspot.com In just one album, this female-fronted L.A. trio has done what it took similarly staffed East Coast superstars the Yeah Yeah Yeahs three records to pull off. They’ve gone from making garage rock to synth-pop, and while their transition has been less spectacular—they were never as explosive as the YYYs, and they’re not as experimental now—the change has been for the best. On tunes like...