The increased pricing of each new Synergistic fuse is pretty strong evidence that the game afoot here is expectation bias, leveraging trite, shallow assumptions that you get what you pay for. and newer is better.
The money-back trial is just a math equation for extremely high-margin products. If If the guarantee doubles the number of trials, you don't care if some (or many) are returned because the net profit is massively increased. And if you're marketing something as elusive as sound perception then once-bought, the product is often kept because it might be making a difference.