Fuse upgrades? -- 6.3 amp 250v 5X20mm fast blow fuses

auxinput and sleepwalker,
Much obliged for your thinking on this issue.  I tried a couple of SR Black fuses in a former amp and preamp and perceived no difference in sound.  I have some Hifi Tuning fuses in other gear and never think much about them, but I might get a set for my McCormack.  It seems for every "fusehead" around, they are just as many EE's and other tech's who scoff at the idea of fuses making a meaningful difference in sound.  This controversy will never be settled, and while I won't pop of the SR fuses, less expensive one like Hifi Tuning are a fair gamble.  Again, Steve McCormack is a believer in SR fuses yet the fellow that created my preamp thinks it is pure folly.  I am somewhere in the middle.   Thanks again your all your posts.  

auxinput and sleepwalker,
Much obliged for your thinking on this issue.  I tried a couple of SR Black fuses in a former amp and preamp and perceived no difference in sound.  I have some Hifi Tuning fuses in other gear and never think much about them, but I might get a set for my McCormack.  It seems for every "fusehead" around, they are just as many EE's and other tech's who scoff at the idea of fuses making a meaningful difference in sound.  This controversy will never be settled, and while I won't pop of the SR fuses, less expensive one like Hifi Tuning are a fair gamble.  Again, Steve McCormack is a believer in SR fuses yet the fellow that created my preamp thinks it is pure folly.  I am somewhere in the middle.   Thanks again your all your posts.  

sleepwalker65" I am very well-informed, having an engineering background and work in the broadcast media industry. I know what limits the DC power supply places on sound quality, and fully understand the ramifications of placing a weak link in the chain of power delivery. Your comments betray a lack of understanding of how power supplies function.'

Your posts are those of a fake, a phony, a person "pretending" to be an expert when it is apparent from this post and your previous renderings on this site that you are confused, disoriented or just misinformed many posters hear are actually in elementary school and you would appear by all evidence and available examples to be one of them but I suppose you are having fun which is fine but other's here who are experienced, knowledgeable and informed are free to question, challenge, and refute your pronouncements, declarations, and edicts. 

sleepwalker65
You can choose to believe in unquantifiable properties, while I believe in the works of the esteemed scientists who authoritatively laid the groundwork of all modern electrotechnology: Georg Ohm, Heinrich Hertz, James Watt, Joseph Henry, Alessandro Volta, André-Marie Ampère, Michael Faraday, Charles-Augustine de Coulomb, Nikola Tesla, Gustov Kirchoff, Thomas Edison, John Bardeen, Walter Brattain, William Shockley and many others. Believe what you want to, but please refrain from disparaging others.

Best Name Dropper of the Week goes to....sleepwalker!

Joke. Who invented the steam engine? Watt. Who invented the steam engine? Watt. Who....

Couple of additional thoughts.  You may not hear a difference with fuses.  Your equipment/speakers may not be high enough resolution to hear the differences.  On very warm equipment, just putting in one Hi-Fi Tuning fuse may not may any significant amount of difference (especially if there are 3 other fuses that are working in conjunction).  If you have 4 internal fuses on the DNA, I would suggest upgrading all 4 of them to get an "idea" of what a specific fuse is doing.  I suspect they are all post-transformer or post-regulator fuses (2 for each channel).