For high NRG Chicago blues; Buddy Guy's "Damn Right I've Got the Blues" is great with lots of guitar fire power-- his version of "Mustang Sally" is killer, and BG is a living legend. For a softer sound, but still "Chicago", try Otis Rush's "Lost in the Blues". I also really like Koko Taylor's music, but it's much more "vocal" than instrumental. Happy Listenening. Craig.