For most people, amplification of the musical signal means just that. Taking the original signal as generated by the source and making that signal bigger.
Only, that’s not what happens.
In the same way the energy from your leg pressing a gas pedal is not actually amplified in the movement of an automobile, it would be more correct to think of it as being translated rather than amplified.
Why is this important? Because understanding at a fundamental level that an audio amplifier is a power supply whose output valve is controlled by the input signal shines a bright light on the importance of the valve and the power supply rather than focusing on the input signal.
Going back to our car analogy, we shouldn’t care about the quality of the shoe used to control the gas pedal. Instead, we want to focus on how perfectly the translation of our foot’s instructions is carried out by the car’s drive train.
It’s the translator that we should be focusing on as opposed to harboring the notion we’re somehow preserving tiny signals in their original form.
Thus, we designers must pay strict attention to the power supplies that feed downstream stereo equipment and the responsiveness of the valves used to regulate the flow of their power.
It’s all in the translation.