There's no denying the historic significance of the 1969 Woodstock Music and Art Fair. There had never been anything like it, and many would argue there's not been anything like it since. With an unexpected crowd of over 400,000 people, there was a lot that could have gone wrong and some things did. But one aspect that's nearly universally agreed upon was how great all the musicians sounded. That sound quality is thanks in part to the McIntosh MC3500 Vacuum Tube Amplifiers that exclusively powered the sound system used at Woodstock. The MC3500 would go on to power many other influential music events.