The Beatles at Shea Stadium (1965)
The Beatles' concert at Shea Stadium in New York City in 1965 marked the first time that a rock band used a sports stadium as a concert venue. This event had 55,000 attendees, 2000 security personnel, and a record-breaking $304,600 gross; but the most important number was 100 — that is, the custom 100-watt amplifiers that Vox made for the Moptops' tour.
Overwhelmed by the huge stadium and the frantic screaming fans, the amps couldn't cut it: Even with the support of the in-house PA system, concertgoers simply couldn't hear the band. What's more, the Fab Four couldn't hear themselves, either, which led to shenanigans like [[xref:http://www.youtube.com/watch?v=JwqTrtri1J0|John Lennon playing the keyboard with his elbows|The Beatles I'm Down - Live at the Shea Stadium]]. From here on, live rock shows got even bigger — and so did the speakers.