The job of a fuse is to blow when needed to prevent damage to the gear. So your fuse $$$s may well go up in smoke as designed at some point.
Also fuses are delicate devices that age and wear over time and require replacement at some point to function properly. So often when one hears a difference replacing any fuse a with a new fuse b that is the most likely reason for hearing a difference. That and the fact that merely reseating an existing fuse can improve the contact and make a difference. Saw this all the time even on cheaper gear in years passed replacing fuses for customers at Radio Shack and Lafayette Radio. Replacing old fuses with new was a standard maintenance thing in that fuses typically are not expensive and easy to replace like a pair of worn windshield wipers on a car.
Also fuses are delicate devices that age and wear over time and require replacement at some point to function properly. So often when one hears a difference replacing any fuse a with a new fuse b that is the most likely reason for hearing a difference. That and the fact that merely reseating an existing fuse can improve the contact and make a difference. Saw this all the time even on cheaper gear in years passed replacing fuses for customers at Radio Shack and Lafayette Radio. Replacing old fuses with new was a standard maintenance thing in that fuses typically are not expensive and easy to replace like a pair of worn windshield wipers on a car.

