Synergistic Research Black fuese

As a rule I always go one step higher now when installing SR Blacks

Thanks for the reply, I'm oversea and wont have the luxury to exchange like you.

My power amp has 4A for main supply and 2x 6.3A for the rail. Do you recommend to go one step for all or the main supply only?

Shouldn't one consult the manufacturer to make sure going "one step up" in the fuse is in fact safe?  Means with a surge more current will go into the component before it is cut off by the fuse blowing.  Isn't that a safety issue for both the component and whomever is near it??

Excellent point. I agree that if in doubt speak to the manufacture first.  It's the safe way to go.

I can logically explain  the reason why better fuses sound better .
With yhd Blacks they use the nano Graphite coating which I have followed for 
Over 2 years now Nasal Developed and used in the best 3d printers, super conductor capacitOrson, Nasa Wiring . Synergistic uses it a as a coating .
It is many 1,000s denser molecular  wise.
Let me back up a moment , if you go online and look up metals resistance
Index ,Silver ,vs the cheap buss fuse is 7x less resistance Copper very similar to Silver in this respect. The steel fuse is loads of low level nois and a Huge bottleneck ,like a 1/8 the inch pipe  vs a 7/8th inch pipe Carrying  water.
Electrically resistance wise a similar effect friction resistance= noise
In simplistic terms. These new Black fuses x100 .diminishing returns 
But no matter what fuse.myself had Hifi tuning Black supreme fuses no contest 
The best fuse I have ever used in my Schiit Multibit Gungnir dac ,Aurender player 
Like a upgrade more detail more realistic analog if you will .
In my Pass 1st watt same thing,even my 300b preamp like a upgrade .
Well worth the $$ .parts connecxion will give you $$ off thd more uou buy 
I bought 6 and saved $100 during Xmas sale even at 150 hours still better better.
The nano coating takes 200 hours to fully settle in.