McIntosh fuse changeout to make better sound

This is partially correct, ac does change direction

So does the current.
As I said the only way a fuse can make a sound change is if it were a diode, a bad contact "can " cause a "diode effect".

So to the gullible just do this and save money for better equipment instead.

  Just change the fuse if old for a quality brand EE industry standard 50c fuse, as fuses (even the snake oil ones) do age after many turn on cycle surges.

     Quick blow fuses       and         slow blow fuses aging left to right.
https://ibb.co/0ZtRv4J                  https://ibb.co/mbzs3RK

Cheers George

"Gullible" is too kind.

To be gullible is to think that everything that happens after the fuse's role is done is completely isolated and unaffected afterwards.

George unfortunately you're understanding of electricity doesn't appear to be deep enough to have this conversation. you are trying to use AC as a justification for the fuse not being directional but that is a false argument because the fuse isn't directional is actually why AC doesn't matter.

I do find the claims that people who did not believe in fuses must not have tried it because many of us have I have many times with many people that's why I'm pretty confident about my position. What I'm also pretty confident about is that all the people who claim that people who don't believe infuses have never tried it have never themselves actually done a proper blind test a fuses after cleaning the contacts. So to them I say unless you've actually done a blind test and have cleaned the contacts you actually haven't done the test.

For marketing purposes, it's a great idea to produce a product that claims efficacy and back it up with hyperbole with a qualifier like "if you can't hear a difference you or your system is/are inadequate somehow." The fact that ridiculously expensive "magic" fuses are generally ignored by the vast majority of audiophiles and component manufacturers should tell you something. And it's worth noting that no component I know of claims that its internal wiring (including the wiring immediately after the fuse) is utilized with any thought of wire directionality (a box of wire directionality chaos! Oh no!), except perhaps internal speaker wiring, although that's generally not mentioned either.