"Naysayers, you can't go through life using conjecture, insults, snide remarks, and a low and transparent level of sophistry and have any credibility"
+2 @nonoise - You couldn't have said any better. Sadly, it didn't sink in...one member here continue to blah blah his DIY skills based on a F5 clone. I mean anyone can put together an amp with off the shelf parts with proper instructions.
When you think about it, the notion that a fuse can make a difference is not that implausible. If, as most designers of high-end audio electronics will admit, the kind of wire used for a component's internal wiring can make a difference, then why not a fuse? After all, the job of the fuse is to melt when a certain level of current is reached, so might there not be differences in how various fuses react to current at lower levels, possibly constricting or otherwise influencing the power used by the component?
Based on my experience, the stock fuse don't sound bad, in fact they sound just fine. In my system, upgraded Fuses improved the overall sound with slightly better dynamics and transients.
As with any tweaks, the level of improvements may vary based on the components design and overall implementation.
If you hear a difference with upgraded fuses keep them, if you don't then simply return them. It's your money and your system, do what pleases you to make it sound better!
Peace out!