Progressive bluegrass combo Punch Brothers settle into a hybrid sound with a sharp melodies

I’d hoped to make it through my life without hearing a host of A Prairie Home Companion break out in a rap, but with the new Punch Brothers album All Ashore (Nonesuch) that desire has been shattered. Toward the end of the second song, “The Angel of Doubt,” mandolinist, singer, and inheritor of Garrison Keillor’s maligned throne Chris Thile switches from a sweet falsetto to a wooden, hopelessly ofay rap cadence.…