fuses - the $39 ones or the 85 cent ones

Treating the room should be on the short list.
And, Bass traps aren't that difficult....Corner traps and cylinders are fairly easy.

I just suggest that the right order of operations is room first, than 'icing', if you can even demonstrate differences in fuses!

I don't mean to be harsh, but saying it don't make it so.
Every double blind drug study features a small %age of people getting well on sugar pills or sugar water.

Any room treatment I have done has been obvious and easily heard. Even the spouse, who couldn't care less, makes note of the big changes. She wouldn't say it if she didnt' notice, either. She is pretty honest about these things.

Have fun with hundreds of $'s in fuses, but I think the money could be better spent on the room, 1st.

Magfan, certainly your saying that fuses don't matter don't make it so. Don't mention double blind tests as they are invalid tests for audio. Stop mischaracterizing what I am saying. I have never said that having a good room is not a top priority. I have said that your characterization of room treatment being inexpensive is utter nonsense in my experience as "cheap" treatments don't treat lower frequencies and in my experience at least take the life out of the music. Bass traps are hardly high in WAF and tube traps are one of the worst things I have ever tried.

I am happy for you that you are satisfied with what you have done with room treatment, so am I after all these failed efforts. I would not be discriminating between Hi-Fi Tuning and IsoClean fuses if I did not hear a difference. You seem to want to argue about some efforts being easy to hear and others not. Have you compared fuses and had a hard time hearing any difference? If you have, fine don't buy better fuses. Your experience, however, may not be that of others. If you have heard the fuses than shut up.

Don't question Tbg on the treatment of his room. See the photos on his system page for further info.

Good, A properly treated room should be done 1st.
If you have a properly treated room, than on to the next project. My personal space, in a small house, has 8 walls, 2 at 45's, and an asymetric vault ceiling. Either an amazing opportunity or a nightmare. About the only major positive is that I don't have any real bass 'hot spots'. When I first put a system in this room I had an echo from the far, short wall.
Since I was in debt up to my nostrils, my treatment of choice was a small woolen tapestry hung about 2" from the wall. That helped imaging etc etc no end.
My next project, nearly 2 decades later is the purchase of some OC703 to treat 1st reflection points (1 wall at 45 is about 11' tall, maybe 12' from RH speaker....)and between the speakers. A local hi-end store demo'd w/ and w/o such treatment and it is clear Maggies benefit enormously from this...the backwave from them makes for some unique problems.
My point in dragging DBT back into this is that the PLACEBO effect is alive and well and living in everyone. Does my car feel better after an oil change / wash job? Yep! Is anything really different? Nope

All you gotta do is leave the room while a trusted friend does or doesn't change the fuses.....Do this 10 times over a period of 5 or so weeks and see if you can tell more than a chance 50:50 A score of 90 is definitive and warrants a good crow eating. 60% is still within chance. For validity, you really need more like 20 trials, but for the sake of arguement, 10'l do.

I'll also check out the system pics.....Without even looking I KNOW there are a bunch of good room treatment ideas, stuff I never saw or thought of. Maybe some of them will increase the WAF, 'cause I see problems with room treatments!
I'll also admit to some jealousy, in advance. I simply don't have the space or money to make a dedicated HT / or listening area. Everyone that simply isn't near-filthy rich has to compromise. I know most everyone here has done so.

I have not read this whole thread so maybe some of this is redundant.

I would say the results vary quite a bit.
Obviously it also depends where in the circuit path the fuse lies as to how it will effect sonics (as well as the particular circuit as well) and the resolution of the system.

In my PS Audio Solid state control amp - the Hi FI fuses provided a nice improvement that was subtle but noticeable.

On my ATma amps the fuses (one of which is in the signal path to protect from tube blow outs) were a large improvement in inner detail among other aspects- and was not at all subtle. I have suggested these to other owners , one who thought it was a much bigger upgrade than going to better power cords.

I put them in my sub's amps and I can't really tell if there was an improvement (though I didn't then pull them out and listen again- so who knows.)

These companies should create a user database for people to fill in what component they upgraded and what the improvement was. I think it would help people to feel confident they were getting their money's worth.

But to me the cost is small enough that if it makes 50% of my components better - it's money well spent. This goes against the law of diminishing returns we often speak of. If $80 in fuses makes my 14K$ amps even 10% better, it's worth the trouble.