If you have been an Electronics student in your youth, audio amplifiers are probably one of the first practical applications of this discipline you have run into.
When you understand the potential of Electronics, you become eager to build something with your hands. You know well that the satisfaction you get when you see your creature working—no matter how much time and energy it has cost—is just priceless! So you start looking for a cool project to put your hands on. Since almost everybody likes music and because it requires few notions, often the Electronics students choose the audio amplifier as their own “baptism of fire”. Some of them click during this experience. If this happens, they’ll likely join the audiophiles community then. Tons of resources—websites, forums, chat rooms etc.—are available on the Internet, dealing with these people’s passion, defined as
high-fidelity sound reproduction
I am not and I have never been an audiophile. However, I have read a lot of stuff and I have built some audio amplifiers (class D and T). I think that this world is really fascinating. Even if it is based on solid technical and scientific knowledge, the human factor is dominant. At the end of the day, in fact, the perception of sound is a process that involves psychological responses, as well as physical mechanisms . As a consequence, it is quite different with regard to the other typical fields of engineering, because objective criteria (such as instrumental measurements) are not enough to determine how good a product is .
All of this provides designers a great freedom to find esoteric solutions and to experiments innovative ideas. An outstanding example of this approach is the great AmpDiVa technology developed by my good friend Marco Rampin. He has been able to combine the use of vacuum tubes, fiber optic cables and digital amplification in one product! Amazing! I’m really happy for helping him a little bit at the beginning of the project. His amplifiers—also available here as development kits—have been acknowledged as one of the best projects of the Maker Faire Rome 2015.
 Psychoacoustics studies this matter.
 Of course, this is true for the amplifiers but it holds for other devices of the audio chain as well (i.e. speakers and cables).