I was with Matthew Poes and sat through a sales pitch where a guy tried to sell us some wood chips to improve the sound quality of our system. They were pieces of wood that you could just set anywhere in your room and they would absorb the bad quantum vibes to make the sound better or something like that.
These things.
Just a little later, we sat through another sales pitch where a guy had a pneumatic pump under his equipment rack. He would raise the equipment rack with the pneumatic pump, and then slowly release it to little it settle back down. The resettling process was supposed to remove built-up resonances or some such techno-babble. Good times!
I have had a lot more experiences like that, from magic power cables, to magnets that you set up around your speaker cable to keep out EM noise, to quantum air purifiers that make the air better for sound transmission. There are too many to remember.