Why 70's stereos rocked and 80''s stereos sucked

[Progressive dog]

5. Most 70s stereos

used heavy power supplies because the transformers needed iron cores to work at 60 Hertz. Newer amplifies are lighter and cheaper for the same quality and power. They don't need the iron because the 60 HZ is converted to DC and the DC is converted to a higher frequency before being transformed. There are no output transformers.
Amplifier specifications have improved, receiver specifications have improved.