In the late 1960s, as white rock musicians were making a fortune off music that largely aped the sounds of American blues, some original bluesmen smartly recorded albums that courted this new audience.

Perhaps the most prominent example of this is Electric Mud, on which producer Marshall Chess put Muddy Waters in the studio with Charles Stepney, mastermind of the Rotary Connection and later Earth, Wind & Fire, and Pete Cosey, a monster of a guitarist who would go on to play with Miles Davis.

They cut eight tracks, mostly psychedelic reworkings of Waters’ classic songs and a cover of the Rolling Stones’ “Let’s Spend The Night Together.” The result was Waters’ first album to hit the Billboard charts, but critics dismissed it as disingenuous. Waters agreed; he called it “dogshit,” complaining the album wasn’t proper blues and that his backing band lacked the equipment—large amplifiers, effects pedals, etc.—to play it live.

But other musicians picked up on it. Jimi Hendrix, who Electric Mud had sought to imitate, was a fan—and it’s even hailed as an early influence on hip-hop. Listening to it today, it’s difficult to believe this album even exists; it sounds like Muddy Waters backed by Blue Cheer—a combination too good to be true.