Furutech fuse

Back story. I find the prices of Synergistic fuses extortion. Like someone charging $100 for a cup of water in the desert. The product may have value as a tweak, the materials do not justify the price to me. 

However, ever the tweaker, I succumbed to buying a $40 Furutech 20mm 4 amp fuse for my preamp.

It’s rhodium plated OFC.

I tried it in both directions. Yes, it sounded more coherent in one direction than the other. I ran it for about 10 hours.

I did not like the sound. Etched and dry with reduced bass. I swapped back the original.

@cleeds Jeez, I did not mean it literally. I used a simile to illustrate how I believe the product is overpriced. 
@elizabeth Indeed. Me too. Years ago, I moved a turntable from a temp location on a concrete floor to a lovingly built oak table. The SQ deteriorated so badly it was horrific.  Yet when I added granite underneath, it was almost back to where it was. I was amazed. I am sure the Synergistic fuses may do as they claim but I do not feel happy about value for money.
“Stuff changes the sound.”

>>>>>Profound. 🤗 
I heard that wax filled fuses sound good. So do fuses with a wrap of masking tape or PTFE. I'm going to try the latter. My guess is the fuse and/or fuse wire is oscillating at the power frequency due to its construction much like a guitar string. Further resonances then dirty the power. Perhaps the expensive fuses are filled with graphene. 
Please be aware that the Furutech rhodium fuses require a very long time to burn in (around 200-300 hours).  After 10 hours, you are already in the "painful" stage.  Keep the fuse in the preamp for another 10-15 days and then do critical listening.  It will actually go through several changes.
That being said, I think a 4A fuse is probably way too much for a preamp.  I would not put in more than a 2A, but I don't know your current preamp model.