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

Fuses have no bearing on sound quality unless they are directly between the output stage of the power amps and speakers. Remember, it is the secondary of the amplifier’s power transformer that does all the heavy lifting (typically 5:1 current ratio relative to the primary winding), augmented by the filter capacitors on more demanding load peaks).

The OP’s problem is probably exacerbated by the design spec for his amplifier fuse leaning towards the conservative side, more judiciously protecting the amplifier. I suspect tolerance of the fuse in that case might be a factor also, making the likelihood of blowing a fuse even greater. If it were my gear, I’d take some current draw measurements to get an idea of how close to the threshold the amplifier is running. Consulting with the manufacturer would be prudent, in case they have come across other such cases and deemed that a change in fuse rating is warranted to mitigate nuisance blowing of fuses.

The problem is usually that the fuses (any fuse) cannot be easily made to complete their required job successfully and at the same time handle large transient functions. No one has done it so far, not any ’audiophile’ fuse, either, unless they skirt the edge of proper legal descriptive and actual function of a fuse.

To add, they are highly non-linear, at best....quite large non linear odd order distortions, when under complex dynamic loading, which is what is inside an amplifier.

Tests done with thin wall 99.99% copper tubing as fuse substitutes (found at the given local hobby supply shops), illustrates quite dramatically...just how bad fuses sound. It almost sounds like a double or triple equipment upgrade. It is not subtle. I exaggerate, but not by much. Depends on how the given listener...listens, it depends on what they listen for.

Doing this experiment is not recommended, as one would be incredibly tempted to leave said test devices in place. Unstoppably so. (one would be begging for just one more minute of that incredible sound....!) Unhearing this is pretty well impossible, and will haunt one forever afterward. Do not do this unless you wish to be ruined.

But all of that aside, audiophile fuses sound better than any stock fuse, including Bussman and Littelfuse. Do all audiophile fuses sound alike? Heavens, no! But they’ve come a long way, baby! That’s why audiophile fuses are more popular than ever. You know, with around 30-40,000 in the last few years alone. Hel-loo! Go, ahead, do yourself a favor. Don’t be a cube, rube. Hop on board the fuse train. 🚂 Toot! Toot!

Can’t do this, can’t do that, too complex? Whoa, what’s with all the negativity? Don’t say can’t. Be like the Little Train that could. 🚂 Toot! Toot!

sleepwalker65"Fuses have no bearing on sound quality unless they are directly between the output stage of the power amps and speakers."

Yes we can understand that this is your faith, belief, and unshakeable conviction and that your belief is based on what you feel to be reality based on certain information available to you but that is limited in scope, authority, and completeness but what I recommend you undertake is exploring the real world that exists outside of your little computer before pronouncing hear your ill-considered conclusions that are derived from source(s) you don't even bother to reference, identify, or substantiate. 

@clearthink 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.

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.