McIntosh fuse changeout to make better sound

That would make too much sense for some.

"This is partially correct, ac does change direction, but the EM wave does not."                         The fact that voltage/signal flows outside the conductor, as a wave, and always toward the load, doesn't fit their 1800's science based theories of AC electricity.                       They're still trying to shove electrons through conductors (waveguides).     https://en.wikipedia.org/wiki/Speed_of_electricity      Note what's stated under 'Electric Drift', regarding AC and electrons.         Save your keystrokes, as any modern science/theory will be categorically dismissed, by the Naysayer Doctrine adherents.

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.