Tom Krell inspired a fertile new subgenre with Love Remains, and he affirmed his ability to evolve with Total Loss. Still, he’s never offered an inkling that he’d reach such heights so gracefully. “What Is This Heart?” — more like “What Is This Album?” Here we have an unimaginably gorgeous, utterly unique advancement in modern music: Art-damaged, R&B-informed singer-songwriter soft rock, marked by walloping bass and fragile falsetto, tackling the tactile and the metaphysical with vulnerability and verve. Krell says God doesn’t exist, but this music might disprove that thesis. –Chris