What is the science behind audiophile fuses?

In the entire power chain, from nuclear reactor through to your component, the piece with the greatest resistance to flow is the fuse, at least among the pieces you have any control over. It would logically follow that assuming input power had any effect (a whole other topic!) it would be the fuse that has the greatest effect.

@mitch2 I've trusted copper.  I make my own slugs from high conductivity copper I buy from Mcmaster.  It isn't very expensive.  I haven't bothered with silver or graphene slugs.  I know people trying slugs made of worse conductors like brass or even steel alloys.  these are much worse conductors than copper but much better than a fuse (becasue of the cross sectional area).  So I know there are lots of opinions here but I stick with copper.

Jerry

@pproctor You are correct.  the fuse is indeed the biggest resistor in the entire line.  (there is some voltage drop over the long lines).  so that is why we want to repace or eliminate it.  

The best option is to find something that provides protection but isn't a resistor--thus the SDFB.  

I like on many components that I don't expect to fail, to just raw dog it with no protection and replace the fuse with a slug (some think this is crazy, they are entitled to their opinion). 

and finally, there are expensive boutiques fuses that try to protect your gear with less negative effects, with limited results.  

Jerry

When my amps were finished in 2020, SMc Audio had begun doing away with power switches (mine have none) but it wasn’t until a year or two later that they found magnetic breakers that they were comfortable with using to replace fuses.  Apparently they ruled out more than a few manufacturers/models that didn’t sound so good, until they found one they liked.  The magnetic switches they use, like in my SMc DAC-2, serve three roles:

1. Over-current protection for the equipment
2. On/off switch (although less conveniently located on the back)
3. Delay to resist blowing due to in-rush current upon power-up

Their source is proprietary but I am going to receive two of them (10A) that I plan to use for a solution external to the amp chassis, but that will not require an extra power cord like the SDFB.

My experience using Sluggo’s is that they are similar to tubes or cables. Each metal has it’s own sound signature. Copper warmer, silver more detailed and revealing, silver/rhodium hollow in between. But the graphene/copper slug was another “Oh My” moment and made the biggest improvement in SQ. Sluggos take many hours to break in and as crazy as this sounds some sound different if you switch their direction after break in. I am somewhat in Carlsbad2 camp where I only use the SDFB for my tube components with rectifiers. All other components with power input fuses I use sluggs without protection. I feel the very low risk of failure and the cost to repair the component is cheaper than buying more SDFB’s. I have never had a power input fuse blow just internal fuses protecting rectifier failures. Some are connecting a single SDFB to a splitter or outlet box and plug in multiple components with the same amp rating to avoid buying a SDFB’s for each component. Not sure of the science to it all but Sluggos do make a noticeable difference in SQ.