fuses - the $39 ones or the 85 cent ones

I hope this fuse of which you speak is not a line fuse. If it indeed a line fuse there is no reason to pay more than a couple of bucks max. The idea that a line fuse made out of gold will somehow improve the sound is ridiculous. What exactly do you think is the cause of this supposed improvement? If you cannot identify the cause of the improvement and somehow prove it (hopefully by application of mathematics like the rest of engineering principles are proven) then you are merely opening yourself up to countless scams. If the goldenn line fuse is going to improve the sound, then why would it not be equally important to keep the operating environment at very precise temperature and humidity levels - or install ferrite beads around all speaker cables and power conductors, or replace all soldered connections on your pcb's with silver solder, or better yet, build a faraday cage around your listening room. My point is that without having an explanation for these useless tweaks the only limitation is one's imagination, or more precisely, the imagination of the person proffiting by the sale. One reason that science is usefull is that it aids in making judicious choices. The proof of science is in the so called pudding. Space travel, digital computers, MRI's, cell phones, etc etc all are possible not through subective what ifs but through predictable outcomes arrived at via a scientific approach. It is not the case that we generally observe a phenomenon and then later explain it with mathematics but rather that the mathematics explain what is possible before the technology catches up.

Someone's been boning up on the Skeptics Handbook. and offering up the usual Strawman arguments.

Don't hold back, Musicnoise!
One bit of science you missed is the idea of repeatability.
When I add 2 plus 2, I get the same answer as anyone on the planet.
When you take a match to a balloon full of hydrogen and oxygen, in the proper ratio.....BOOM, you get a little puff of water vapor....every time.
There are various ramifications of all this tweak stuff.
That there is no concensus about anything...even as simple as a fuse, for Pete's sake, is a sign to me of extreme subjectivity and Weird science.

I am building a Faraday Cage around my house, even as we speak. I'll have 10ft Copper Ground rods driven by the end of the weekend and borrow a 'megger' from work to test the resistivity of ground. I'm sure this will remove the last bit of remaining haze from the upper octave.

By the way, if I am mistaken as to the location of the fuse of which you speak, and it is indeed neither a line fuse nor, for that matter, a fuse for one of the rails, then it makes perfect sense that the gold endcaps would make a difference. I was just not aware that any amplifiers used fuses to protect a differential input stage. I would highly suggest that you replace both of the fuses at the same time and purchase only a matched pair.

Musicnoise, your theory does not apply here in highend audio.
The only explanation is what you hear with your own ears!!
Whether it can be explained scientifically, mathematically or otherwise means nothing if you can't hear a difference with your own ears. The proof of science cannot change my hearing!! or what I percieve I hear.