Soul and blues aren’t separate styles so much as points on the same evolutionary spectrum, with soul—and in particular, soul ballads—growing out of a hybrid of blues, gospel, and jazz. However you classify them, the tracks here capture a sense of melancholy and introspection associated with the blues, mixed with the confidence and virtuosity of soul—a powerful combination. Our editors update picks regularly, so if you hear something you like, add it to your library.