Thanks to everyone and your at times spirited responses. And no, I am not a "puppy seal" asking apparently innocuous questions only to stir up the pot. I am a scientist and a curious one at that. I learned that a fuse is indeed part of the circuit, in series, not in parallel: not the signal circuit itself but the part that supplies the power for proper operation. I also learned that the fuse-material itself (alloy, etc.) shares the characteristics of a resistor, one that "blows" when too much current flows through it. As such, it would make sense, that in a highly dynamic amplifier setting, for split-seconds a sub-optimal level of current would be available to amplify the signal in true fidelity. In so far, the use of materials that have less resistance and yet still fulfill their safety-valve function would make sense - at least theoretically. But what about audio practice? Will one actually HEAR the difference? Or let me re-phrase: will someone with average ears (in my case age-relatedly compromised) and a sub $50K system with enjoyable but probably not stellar performance hear such a difference?
Yesterday I went to the annual "Exotics on Broadway" exhibition in Seaside, part of the world-famous Monterey Car Weekend. Exotic supercars and so-called hyper-cars, some of them costing multiple millions of Dollars, are on public display there for everyone to admire and talk to the developers/dealers for free. If you are into state-of-the-art automotive "art", that’s a place not to miss. I do love looking at these cars, I admit. But driving one? My Tesla S leaves still many of them in the rear mirror, and doing so without the ear-splitting noise of a 1,500 horsepower engine. The same goes for my stereo set-up: I tremendously enjoy what I got in terms of delivering listening joy every night - with Bussmann fuses, mind you. But I also know, that certain tweaks can indeed make a noticeable difference: I recently replaced my Mogami XLR ICs with all-silver, shielded ones from Taiwan, and yes: even I with my compromised hearing could immediately hear the difference; and no: no confirmation bias here, which I thoroughly understand on a professional level, and in any case, the new ICs were rather affordable. So, would I be able to hear such a difference by replacing my Home-Depot fuse (which came standard with my all-tube preamp)? Perhaps, but I don’t really think so; also, because exotic fuses - if they have their audio reason to exist - would probably exerting their "magic" in an amp rather than in a pre - and probably in a much more sensitive, i.e. costly, one, than the ones I use. But that I don’t really know. What I do know, however, that as scientists we always stay on the shoulders of giants (Feynman citation, I believe), and yes, a fundamental characteristic of good science is not to be dogmatic (we do not "believe" in science), but critical nevertheless. Let the data speak. In my case, the "data" are being delivered to my analytical brain through my ears, and not through a sophisticated measuring device, which might indeed pick up differences from audiophile fuses, albeit - at least in my case- inaudible ones. So be it: I "measure" performance along the coordinates of enjoyment and cost, like - I am sure - do many of you. And with the data at hand, and your delightful and sometimes informative comments, I will probably abstain of paying hundreds of $$ for a tweak that I might not be able to hear with the gear, and ears, I got. Again, thanks to all!