I may have to try one of these BLUE fuses sometime in my source equipment. Maybe next year because I already have too much stuff on my project list for now.
That being said, there are several good points mentioned here on both sides. The fuse is NEVER going to be a magic bullet to make your system sound perfect. It is a tool/tweak to allow you to tune your system in a direction that you want to go. On the other hand, yes it is only a 1" length of wire, but that wire can have a significant effect on the sound as the unit pulls in A/C current for its power supply (which has a big effect on overall sonic signature).
In my research/testing, there are several elements that can contribute:
- resistance/slew - this affects how fast the power supply can start to pull in current from A/C when there is a drop is voltage. This can affect how fast the audio sounds and can also affect leanness in sound.
- electrical resonance - the fuse will have an electrical resonance/vibration as it charges/discharges. This can affect the harshness of the sound and can also cause sound to be weak/distorted (if there is a lot of resonance).
- metallurgy - this will have an affect the sonic signature just like anything else (such as interconnects). Silver vs gold vs copper vs rhodium vs brass. It all has an influence. For example, a gold plated copper Isoclean fuse can be fine for pulling in large amounts of current, but it may not respond as quickly for tiny/fast changes (which can affect high frequency resolution). This can translate into a warmer/richer type of sonic signature. This is probably hand-in-hand with the resistance/slew characteristic above.