FWIW, I was a fuse skeptic until I tried a Swiss Digital Fuse Box (SDFB) in lieu of the stock fuse in a PSA P10 Regenerator.
Point being, I never observed a discernible difference between stock fuses and SR Orange fuses in some of my kit, but the SDFB (which replaces a fuse - meaning there is no fuse in the P10 any longer - just a metal rod in place of the fuse) resulted in an immediately noticeable improvement to my ears. (Most of my listening is via my PSA DS Sr. DAC.)
It’s been quite a while since the addition of the SDFB so I can’t recall the observations directly, but you can read more about the SDFB in general and my experience here:
Bottom line: If no fuse (with a SDFB and metal rod) is better than the fuses I listened with before, I can now understand that fuses can matter.
Cheers.