https://parttimeaudiophile.com/2020/12/06/the-best-cables-po...
My favorite recent discovery was a device that shaves a bit of plastic off the edge of your CDs to improve the sound quality. The manufacturer makes lots of claims about it improving how the light interacts with the polycarbonate, none of which makes any sense. But we don't need a materials scientist or a physicist to explain why their science is bunk, we can just make a hash of the CD before and after "shaving" it to see that the data is still identical.
If you have 20 dollars, you can find yourself something that makes sounds. If you have 2 million dollars sitting around, I bet these sounded some amount better:
https://news.softpedia.com/news/Transmission-Audio-039-s-Ult...
Those were 2009 dollars.
My "Computer speakers" are a bit crazy, but all together cost me sub $3k for a Neumann nearfield monitor + sub + DAC combo.