In the 21st century the line that separates classical and pop continues to blur. How different are, say, Nico Muhly and the Dirty Projectors? Or Sufjan Stevens and the vocalist/composer Corey Dargel, who released the impressive Someone Will Take Care of Me in 2010? There's an echo of the late, great Arthur Russell’s work in Dargel’s art songs. Each half of this double album presents a set of pieces that are linked thematically. On “Thirteen Near Death Experiences,” Dargel, joined by the International Contemporary Ensemble and drummer David T. Little, explores hypochondria and other issues. The second set, “Removable Parts,” which finds Dargel accompanied by pianist Kathleen Supové, looks at the unlikely subject of voluntary amputation. Herky-jerky rhythms and catchy string figures mark “Touch Me Where it Counts,” which expresses the erotic feelings of a patient for his doctor. “Ritalin” deals with the flattening effect of the drug as handclaps interact with ensemble playing. “Fingers” evokes a stranger, more complicated Stephin Merritt song, and in its own way, it’s just as catchy.