Can any of you explain why an item such as a fuse, which breaks the signal path, has such an impact on sound?
As far as I am aware no such explanations have ever been provided that would stand up when analyzed or considered quantitatively. That includes the extensive set of measurements of numerous fuses that have been provided in the past by HiFi Tuning, which I commented on earlier in this and other fuse-related threads.
Although of course all kinds of "explanations" can be, and have been, conjured up that by their nature cannot be analyzed quantitatively.
Also, even if differences in any measured parameters were in fact great enough in degree to have a reasonable likelihood of accounting for sonic differences in some applications, it would STILL not be explainable how they might consistently work in the direction of making a positive difference (rather than a negative difference or no difference), among components that are very different in design and perform very different functions and are presumably powered by AC having very different voltages and noise characteristics (those voltages in various cases most likely being both higher and lower than the voltages the components were presumably designed to sound best at).
And even if all of the above were in fact explainable, it would STILL not account for the sonically significant directional effects of fuses that have been reported.
On the other hand, though, the lack of a good explanation does not **necessarily** mean that the consistently positive results that have been reported for fuse upgrades are attributable to misperception, expectation bias, unrecognized extraneous variables, or more cynical factors. My guess, FWIW, is that in some cases the reported results are accurate, and in other cases are attributable to some combination of those other factors.
IMO.
BTW, my thanks to Wolfie and OP for the nice words in some of their recent posts.
Regards,
-- Al