Sony XA5400ES fuse directionality...

Are you talking damping factor change for a power supply fuse or in the protection part of the output?
One makes a little sense, the other none at all.
Sine the max current draw is isolated from the output by (presumably) a fair amount of capactitance and the max draw thru the fuse is during 'recharge' that is a little......strange.

What is the alloy of the fuse in question. I believe Littlefuse uses a Zinc alloy which this test beforehand so they get the final fuse resistivity correct per amperage.

I've used test equipment called a 4-point probe. 2 tips used to force a voltage, the other 2 tips used to measure. VERY precise readings of resistivity are possible by this method. Repeatable and process capable (in the most rigorous technical sense) such a metrology tool is used in the semiconductor industry for process evaluation.

Wouldn't wrapping the fuse element in ANYTHING result in it changing the characteristics of the fuse?

I have suggested, in the past, a test to be used for microphonics. Put the test piece in an enclosure with a speaker. Have the same circuit OUTSIDE the enclosure. Using a dual trace scope, do with / without sound subtraction of the signal. Microphonic effects should show up very easily.

If there is a distinct difference, don't let me know about it. I hate throwing up, and besides; what one does not know cannot hurt him.

If a $50 fuse makes a difference, then why not bypass the f'ing thing altogether with a piece of pure copper, silver or gold. Ferchrissakes, if that much disinformation were available to my ears I would have all the watches,clocks, pets, cars, trucks and children in the neighborhood banished before listening.

I'm afraid the above idea would cause a LOT of problems in the neighborhood, AND void my 5 year warranty!
I thank those who stuck to the idea of this post and actually offered some helpful advice. To the others...
at this point I think I am going to have to throw in the towel and call it quits because I have no strength left to fight. I confess.... I just pulled out a Q-tip for the first time in 20 years, and discovered my ears have been filled with peanut butter all this time. I can't hear anything above 100hz, and I'm selling everything but my subwoofer...but you can bet IT will have an upgraded fuse in it! :^}

I thank those who stuck to the idea of this post and actually offered some helpful advice. Bigshutterbug

Really? Which ones were those?
You do have a well thought out system though. So if swapping fuses turns you on, enjoy.