What are fuses used for?

They are used to prevent damage to electric circuits from excess current. A fuse is a fine piece of wire with a selected melting point placed in series with one leg of the incoming AC voltage/current. If an electronic device draws too much current the fuse wire will melt and open. Preventing any AC voltage/current from entering the device. Thereby saving the device/circuit from further damage.

All electronic devices/circuits require fuses at the inputs to the power supplies. The exception being battery (DC) powered devices where maximum current draw is limited by the battery size.

Contrary to popular misconception by the ill-informed fuses (like all wire) have NO effect upon sound quality. To think otherwise is to believe in magic!

Fuses can be used to change or control the sound just like speaker cables, interconnects, capacitors, power cords or any wire or cable. Capacitors serve a function just like fuses. Yet capacitors are also directional due to the wire running through them. Since all wire is directional, including the teeny tiny fuse element, all cables, capacitors, fuses sound better in one direction vs the other direction. In one direction, that usually cannot be predicted by the user, the sound will be relatively more coherent, more natural and more musical than the other direction.

This proposition regarding directional can be illustrated most easily by reversing the direction of interconnects and evaluating which direction sounds better. Voila! I’m not referring to shielded interconnects, since they have their own independent issue regarding direction.