There are folks (and associated communities) out there with engineering backgrounds and sophisticated industry-standard measurement gear: AudioPrecision analyzers, GRAD headphone measurement rigs, Klippel NFS scanners.
https://www.erinsaudiocorner.com/
https://www.audiosciencereview.com/forum/index.php?reviews/
I realize it's fun to dunk on all of the "crazies" who are tweaking their sound with crystals or whatever, but they are the lunatic fringe.
Ultimately it's not too different from a lot of industries. Of course, folks hawking their products make some ludicrous claims at times. Just like car ads promise you a happy life with your family and dog if you buy a Subaru or Ford or whatever, there are some wild claims about audio equipment at times. However, there's also a very solid bedrock of actual engineering going on that can be understood and appreciated. And in my experience that's how most people do this hobby.