fuses - the $39 ones or the 85 cent ones

Personally I am more skeptical than most but if Dave_b is happy with his fuse experiment it sure as hell doesn't bother me. Does he believe he hears a difference? Yes.
Do I believe there is a difference? No.
Who's opinion matters? Pretty simple really.
Enjoy your $39 fuses Dave.
I'm happy with my system and am not ever going to spend my time trying to improve it with $39 fuses. The amount of time it would take to conduct the experiment is more than I care to invest. If I want to improve it I'll look elsewhere... new amp, new source, tweak the room treatments maybe.

Well, I am late to the dance, but it seems that all the discussion focuses on the Hi-Fi Tuning fuses versus stock fuses. I have always used IsoClean fuses as they came out well before the Hi-Fis and are or were cheaper. I have twice tried the Hi-Fi Tuning fuses versus the IsoCleans. IMHO the Hi-Fis are second best. I also confirmed to my satisfaction that the Hi-Fis are directional but that there is nothing about them that predicts which direction is best. All that you can do is to try all both ways. This is a real pain. The IsoCleans have clearly marked direction and in using about 20 of them, I have never found any mismarked. I first started trying different fuse direction at the request of Lloyd Walker with his motor controller.

I have also committed the sin of treating fuses with AudioTop contact cleaner and most recently with the Enjoy the Music award winning AVM paint. You only paint the glass, of course.

I have found all of this much more important than ac power conditioners and almost as important as lifting all but one ac ground. Although some recommend lifting all grounds, I have not found this to be best.

This stuff is all in good fun and in this case cheap! On any given day whilst deeply involved in the music one may not even care which fuse is in use. Then again perceptions are everything sometimes.

One additional point, than I'll let this one die a natural death.
The point being that, for most people, the listening area is the last thing modified. Place the speakers, and even spend a couple hours dialing them in. Sub, likewise, but maybe worse, depending on room. Squeeze the furniture in and make room for some wife stuff......depending on how treaty negotiations went!
Now, I know there is a lot of surplus money out there. Our discussion of 39$ (Gasp!) fuses would never come up, if for the price of 3 fuses, you purchased enough OC703 to make a half dozen 2'x4'x4" panels and have a good go at treating your room. I suspect I could improve the imaging of my Maggies thru one of these panels on the wall, in between 'em. Another would go on the 'back' wall which has a bad reflection and since my room is Really odd, vault roof, very asymetrical, I'd experiment with more panels in 'first reflection' points.
I am certain that I could make differences that anyone could hear, maybe spend more than those fuses, and end up with a room / stereo SYSTEM.

Magfan, what makes you think others have not treated their rooms and carefully positioned their speakers? I don't know whether the typical room could be improved as much by what you suggest to rival the improvement of the use better fuses. My experience with room treatments is that those that are effective cost much more than IsoClean fuses. What you are proposing is probably on effective to probably 200 Hz, which is not where most rooms have problems.