If you think you might be interested in listening to one of the prime historical precursors to Cray's mix, try picking up a collection by the late, great Magic Sam. Combining the lighter, soul-inflected vocal leanings with the economical but incisive guitar style, charismatic presence, and strong original material, performed by a younger (and prettier!) member of a new generation of urban electric blues inheritors coming up in the mid-60's, it's not hard to see and hear Sam's inspiring influence on Cray. Unfortunately, this talented pioneer, who promised to be one of the future leaders in the genre, died tragically young, so his recorded legacy is not huge, but what is there is very choice indeed.
