Samuel "Magic Sam" Gene Maghett was an American Chicago blues musician. Maghett was born in Grenada, Mississippi and learned to play the blues from listening to records by Muddy Waters and Little Walter. Wikipedia
Blues Unlimited 66 (October 1969) ran a "quick report" on that year's Ann Arbor festival by Jeff Titon in which he briefly commented on Sam's set thus:
"Backed only by a bass and Sam Lay on drums, Magic Sam brought a cold audience to their feet to dance during his numbers. Like Robert Johnson, Sam is capable of making his one guitar sound like two or three, at once. He has an impeccable, incredibly complex sort of chord‑rhythmic-figures which he plays against a typical modern solo style. Behind his voice he will often use chords voiced like a horn section. Sam also has an infectious floating, soaring vocal. Magic Sam seemed a bit dazzled by the crowd's response, especially as he is not an actor who gyrates or preaches or asks "are you with me" etc, to work the crowd to a fever. The music alone moved the people, who weren't expecting it from someone they never heard of, and they screamed for him rest of the evening, embarrassing Freddy King and James Cotton."
Living Blues had yet to "exist" but Dan Morgenstern it for Down Beat 36, 2 Oct 1969 (pps 14-15, 29-30) under the heading of "The Blues Comes to Ann Arbor".