Certain things must necessarily be done in a studio because there is no text that can make you understand things without being able to listen to them, and many times the nuances are so subtle that even if a CD of examples were attached to a text, you wouldn't be able to hear them without the listening experience provided by a studio. Listening is something FUNDAMENTAL. This is why studio monitor speakers can cost up to 30,000 euros per pair. The reason is truly simple: they allow you to reproduce all frequencies with a linear response, so everything can be heard. This cannot be separated from acoustic treatment of the room, because if the speakers sound good but there are resonances and/or cancellations present in the room, then the 30,000 euros spent on the monitors become perfectly useless (We are talking about main monitors). Nearfields should then be added. As far as I know, in professional studios—and I have visited many—everyone has Yamaha NS-10s, which are terrible monitors, but if once the mix is done on the mains and it sounds good also on the NS-10s, then it sounds good everywhere. If we are talking instead about mastering and/or restoration studios, things change because the equipment is something that sits between pro and hi-fi. Speaking of aesthetics, everything depends on what the musician seeks. One cannot ignore the very close relationship between the musician and the engineer. The musician does not want to hear talk about frequencies, positioning, techniques, and theories; the musician has a reference sound in their head, often incorrect; the engineer is the one who must optimize the work to give the image of the sound in the musician's head, and he knows how to do it. It often happens, as I was saying, that the sound desired by the musician is not "right," and by "right" I mean in relation to the masters of the same genres already on the market. Sometimes it can be a choice, so in some cases "the donkey is tied where the master wants," while in other cases, when as I said, a close relationship is established between musician and engineer, the engineer can propose sounds, obtained also from proper microphone positioning, and create differentiation. Other times, solo musicians arrive in the studio already knowing a standard, even if they know nothing about series positioning: "I have always recorded with this microphone because I like its sound." In this case, the engineer's task (if they mean that type of microphone) is greatly reduced since the placement consists "only" in searching for the instrument's snap point, which varies from musician to musician and from instrument to instrument.
If we talk about recording, then there are various techniques...
There is a famous company—whose name escapes me right now—that performs recordings using only two microphones. The results are incredible because instead of using multiple appropriately positioned microphones while keeping the instruments in a random position influenced only by the visual aspect between musicians (e.g., the bassist must be able to see the drummer, the guitarist must see the bassist, etc.), the microphones are fixed and the position of the instruments is varied to define a focal point upon which the general sound is balanced on the microphone capsules. The microphone furthest forward has a cardioid polar configuration. Immediately behind it, another microphone is inserted in an eight-pattern configuration, also called bidirectional. Consequently, the first microphone will provide the front image, and the second will give us the ambience; there is also a technique to widen the stereo spectrum once the recording is made, which I won't go into detail about here. However, this microphone technique is truly difficult to implement because it requires very advanced theoretical knowledge of acoustics, and for this reason, it is not aimed at amateurs. Then there would be all the discussions regarding the audio chain of preamplifiers and signal routing. There is a world of electronics and computer science to tell, and a forum is the least adequate place for it.
Many believe, as with music in general, that the skills to be acquired are simple. They do not realize that one must have skills in electronics, computer science, and acoustics, and all are linked together in order to obtain a sound that pleases the ear.
I would like a discussion to open here in the forum aimed at the many topics concerning not only music but also sound. If there are questions, I am willing to answer them, if I am capable, that is...