What is the science behind audiophile fuses?

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).

Reading through this thread leaves me open to the possibility that line fuses, being essentially variable resistors, may have a discernable effect on sound quality. If so, the difference is likely to be confined to fuse vs. no fuse, such that replacing a Bussmann fuse with an "audiophile" fuse is likely to be of no import since the latter is still a variable resistor. So I would have to agree with @carlsbad2 's quote above.

The best way to achieve this, though, is not to install slugs of various metals that can’t possibly make any audible difference, insofar as they are cradled in uber-cheap fuse holders made of common steel. Desoldering and tossing that 10 cent fuse holder and jumpering a length of appropriate gauge wire in its place, thus essentially hardwiring your power cord to your equipment's PCB as @mitch2 suggested, seems the sensible way to go.

As far as the Swiss Digital Fuse Box, it answers the safety question, but it seems highly unlikely that any device sitting inline with your power cord AND needing a 2nd power cord in order to function would not impart its own sound signature onto your system, just like power cords themselves have their own sound signatures.

Can the Swiss Digital Fuse Box be truly neutral sounding, or is swapping it for a fuse a case of robbing Peter to pay Paul, so to speak?

How about magnetic breakers, can they be free of effects on sound quality?

It is of course easy to take the fuse thing to absurd extremes that attract scorn and ridicule, but there is a sound case to be made for eliminating them - in a way that ensures safeguards remain intact of course, or are even improved. Fuses are not that good at doing their jobs anyway, so it is interesting to read about what can be done to improve upon the current situation.

@devinplombier I agree with most of your thoughts above. I assume by "variable" resistor, you mean that it changes depending on what current rating it is.  

I will explain that the SDFB is basicly a relay with a magnetic current switch to open it (thus, the same as a magnaetic breaker).  So when closed, it is just a pair of contacts in line with the power. So if a good relay, with high power handling and good contacts with essentially zero resistance is chosen, it should be just about like a straight wire.

If you can find a magnetic breaker to put in the line I'd like to see it.  I couldn't find one that would work.

Jerry

@carlsbad2 

We are on the same page. Electrically, a closed relay is definitely equivalent to a straight wire.

So are power cords, but folks still heatedly argue about them.

If we accept that power cords - the essence of a straight wire - can have a sound signature, whether based on brand or copper purity or braiding style, it seems fair to assume that a more complex device inline with a power cord might also introduce its own sound signature.

Re magnetic breakers, I was just following along with @mitch2 's comment:

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.

I for one am curious to find out how his experiment turns out

Let's assume for a moment that we know what the "filler" is in an Audiomagic M2 fuse. Some rumor that it is graphene loaded beeswax.

Can anyone here scientifically speculate about the effects thereof? I know how the fuse sounds, but how would it be achieving that sound and why would that sound be different from a bare fuse wire?

@devinplombier 

I for one am curious to find out how his experiment turns out

I will be happy to share how my installation of the breakers turns out, but I probably wouldn't categorize this as an "experiment" since SMc Audio are currently and successfully using these breakers in the amplifiers they construct and also in the amps that they upgrade.  In fact, I have the same type of breaker (in a lower 1A rating) in my SMc DAC-2, that I received from them last year.  Pics posted on my system page.

The only difference with the install for my amplifiers is that we decided it would be a cleaner and equally beneficial application for me to use the breakers outside of the amplifiers while replacing the fuses with slugs.  Even though I am fairly comfortable self-performing such things, installing the breaker internally is much better accomplished as part of a new amp build, or an upgrade (a process that involves SMc removing all the inside components anyway) than as a customer-installed retrofit.  After discussing what was involved with SMc, I decided not to fiddle around inside of the amp and especially if I can achieve pretty much the same result with an outside installation mounted in a box adjacent to my wall duplex. 

I will share here in advance that, unfortunately, the breakers used are proprietary as SMc Audio spent quite a bit of time figuring out which breakers worked well and sounded best with their equipment.  Therefore, I will not be sharing the manufacturer or model, although it is a 10A magnetic breaker.  I suspect a similar type of breaker is used inside of the SDFB, and it is probably not that much different from breakers that other manufacturers may use currently.  I remember my first experience with a breaker on/off switch was the thermal circuit breaker in the BPT 2.5 power conditioner I formerly owned.