This is Stevie Ray Vaughan at the 1985 Montreux Jazz Festival. Open Culture has some interesting information about this gig:
In the 1980s, Stevie Ray Vaughan tore through the international music scene like a Texas tornado. His amazingly fluid and dexterous guitar playing on a series of platinum albums established Vaughan as a household name and helped spark a blues revival. But in the summer of 1990 a helicopter he was riding on crashed into a hill in Wisconsin, and the whirlwind had passed.
In 1982, he went to play at Montreux but, since him and his band were virtually unknown outside of Texas, he was booed. Stevie was shaken. But among the boos, Stevie showed the world he existed and this was more important:
David Bowie was in the audience, and he made a point of meeting Vaughan and his manager in the after-hours lounge. John Paul Hammond, the son of record producer John Hammond, also saw the show and asked for a tape of the performance to give to his father. Jackson Browne caught the band’s performance in the after-hours lounge, and he sat in with the group until early the next morning. Within the next few months, Browne invited Vaughan and Double Trouble to his L.A. studio to record a demo, Bowie asked Stevie to appear on his next album [Let’s Dance], and John Hammond, who helped develop the careers of Bob Dylan and Bruce Springsteen, helped the band sign a deal with Epic Records and offered to produce their debut album. The rest, as the cliché goes, is history
He came back to Montreux in 1985 and the show was on.