Well said about the fuse certifications Harby. The advantage of an approved fuse is it has been tested and certified to specific performance criteria according to UL (US) and IEC (rest of the world) safety standard criteria. The advantage of this is every sample of that approved fuse will theoretically operate the same under an overcurrent condition. That being said unless the end equipment, like an audio amp, has been tested by UL, or another safety agency, to the requirements of the audio/ video standards UL/IEC60065 where there they do fault tests to verify the fuse will open consistently under a fault condition having an approved fuse does not mean much. As part of the end product testing UL will induce short and open circuit conditions on components in the amp to make sure there are no potential shock or fire hazards. During the faults, the fuse plays an important part in providing some level of protection that the product will be safe if there is a component failure in the amp. This is where using a UL approved (US) or VDE approved (rest of the world) fuse provides some benefit. If you have a nuisance tripping of a fuse you can feel confident that a UL/VDE replacement will trip under the same condition in the presence of an amp fault. Regarding audiophile fusing I would not assume they just cheap factory fuses marked up to scam unsuspecting audiophiles. I am willing to bet some of these companies have invested time and money to produce a product they believe produces an audible benefit. Unless I have had the chance to compare I will still be skeptical but will try to keep an open mind.