What's improved the most?

A simple question that has often been the subject of debate: if we were to take the various components that contribute to music reproduction, the actual recording, then the turntable/CD player, cartridge, cabling, amplifier, and finally the speakers, then which of these components have improved the most over, say, the last forty years?
Or, another way of putting it: suppose we could assemble a 'super-system' from each of the last four decades, what would the difference be?
To be frivolous, I would say things are potentially more expensive than ever before, but if we eliminate the systems for the uber-rich, what would the results be?