[Eli5] Why do amplifiers require both a preamp and Poweramp stage?

Question

That is, if the preamp amplifies the instrument signal, why is a poweramp necessary at all?

In: 2

Answer 1

In general, pre-amps are used to take very faint signals – such as those from microphones – up to line level, where it can be transmitted short distances, have signal processing applied, etc.

Power amplifiers are used to drive speakers – the actual mechanical device producing the sound – and take the line level sound and amplify it enough to do so.