I will of course say that a fuse can have no effect and this is a complete waste of time and money... and no I don't "trust anyone's ears" on this... If 1000 people all said it was a huge upgrade I'd still say your all imagining it!

The only time a fuse can have an effect on sound is if it is between the output of an amp and a speaker, where they should not be used but sometimes are.

Impossible trumps opinion every time.... No matter whose opinion or how many agree with it... The world remains round even if you're in a room full of hundreds of people yelling at you that it is obviously flat!!

Does no one think it rather suspicious that all "incredible" (literally) after market tweaks come in the form of something that can be simply unplugged/disconnected and then be replaced by the new one by non technical people and without any soldering? Non of the hundreds of other parts in a piece of kit which are soldered in just happen to be the magic tweak?

Now whilst it should be bloody obvious why not anyway, I could write a long technical piece here explaining precisely how and why it's impossible for a fuse to have any effect... but I'll save myself the bother as believers in foo are like any religious believer, in that no amount of evidence to the contrary is going to shake their "faith".