The Crown DC 300 was the first high-powered amplifier on the U.S. hi-fi scene in the early 1970s. For most people with component stereo systems, 20 to 40 Watts per channel was the norm until this monster came along with 150 Watts per side. It was very useful if you liked to play music loud and had acoustic suspension loudspeakers such as AR, KLH or Advent--they had the deepest and flattest bass response, but were inefficient (power-hungry) by comparison with "tuned port" loudspeakers.
Then came the Phase Linear 700 power amplifier ... 350 Watts per channel ...