Sonni had been working at the iconic New York City guitar shop Rudy’s Music Stop in the 1970s when he first met the band’s co-founders, David and Mark Knopfler.
He played alongside the group at 1985′s Live Aid concert at Wembley Stadium and news of his passing, which was posted by the band on Thursday, is prompting a flood of tributes from fans.
Born in Indiana, Pennsylvania, after his collaboration with Dire Straits, Jack went on to contribute to a series of other musicians’ works but ended his professional musical career when his twin daughters were born in 1988.
He began a second career as a marketing executive, first at Seymour Duncan, then Rivera Guitar Amplifiers followed by several years as director of marketing communications at Line 6, a manufacturer of digital technology products for musicians.
In 2001, he became vice-president of marketing communication for Guitar Centre.