In the mid-1990s, Dolly Parton and Ricky Skaggs each turned away from the contemporary country market—and each enjoyed a creative renaissance making rich, authentic bluegrass instead.

Now Ricky is burrowing ever more deeply into the past by offering ultra-faithful renditions of songs by Bill Monroe’s pioneering mid-’40s group. It’s a labor of love carried out with skill and warmth, but it also poses the question: Why bother when the originals are still available?