it's both .. except the mechanical amp does it "analog" and the digital amp likely does it in steps. they both cannot do a proper job.
and i don't like this "challenge me" way the thread is shaping itself because i'm sick of having to explain stuff i paid to learn to people who eitehr 1. do not understand it or 2. do understand it and i don't get paid.
if you go online at the berklee webstore you you find the Glen Ballou book on audio engineering most of my courses relied on. i think it's $100 or so.
it doesn't really go much into physioacoustics (perception of sound) so you'll have to do a bit of research on your own.
a bit.
enough to earn a professional diploma, in, say, acoustics.
i have no idea what EE means, i assume -E is for Engineer. and possibly E- is for Electronics. This should be a walk in the park for you.
1. there is a signal. lets assume this signal is flat.
2. there is an amp. let's assume this amp is flat.
3. there is a signal-receiver (our ears). this is not flat. it changes filter as the amplitude grows.
you want thus the flatness of (2) to remain constant when changing amplitude.
now, as a designer, you have two choices, or in-between. one, you keep the signal (1) flat. this sounds bad because of (3).
other choice, you alter (2) to take (3) into consideration.
Now, you do this by having components which reach to the change in voltage in a non-linear manner, i.e. not completely flat. As these are individual components, they are centered on ..
i really dont enjoy doing audio school for free. THEY ARE centered on a specific frequency. they would have a bell-shaped curve affecting nearby frequencies as well. This means that with analogue components you will never get a flat curve, more so a curve which follows a very specific shape as it changes in amplitude. Not even one that stays flat as it changes in amplitude. essentially you are trying to lift a string with one finger and expecting it to stay flat.
However, we are dumb animals and we like an amp that changes color as it changes volume. we think it has warmth, color, brilliance, and other bs words.
fletcher-munsen curves are also different between people.
digital amps .. have less trouble understanding how they should reproduce a signal. they are more likely to keep to the shape of (3) or (2) as decided by the designer, but as they do not do so by having materials heat up or resistances increase, which we humans like so much.
however, this depends all on how the digital system was designed. generally speaking, professional amp designers tend to use their ears more than digital amp designers, and even if their amps are not accurate, they sound better. Digital amps are the opposite, they are accurate but sound bad.
before i explain why, i would like you to consider how people still prefer valve amps. meanwhile, i'm off to lunch.