Jimmy Page has identified a little-known 1965 track, "I'm Your Witchdoctor" by John Mayall & the Bluesbreakers, as the moment the classic rock guitar sound was born. Page, who produced the song, credits guitarist Eric Clapton with pioneering the pairing of a Gibson guitar and Marshall amplifier to create a muscular, riff-driven tone that broke from the cleaner sound then dominant in British pop. The claim matters because that combination went on to define the sonic identity of the classic rock era, influencing generations of guitarists including Page himself with Led Zeppelin.

Page recalled that Clapton "had all that sound down" during the session, and gave him "total credit" for evolving the style. He also described how the recording engineer, more accustomed to orchestras and big bands, tried to halt the session, declaring Clapton "unrecordable" because of the deliberate feedback and distortion; Page overruled him and took responsibility for letting the tape roll. That decision, Page suggests, preserved a pivotal shift in rock history, cementing the Gibson-and-Marshall set-up as a defining feature of the genre.