Hi-Fi Tunig Fuses & Parasound A21

@geoffkait 
The HiFi Tuning Fuses are marked with an arrow. When I placed the fuses, I put the arrow in the same direction as the flow of current.The stock and Furtuech fuses are unmarked. I did not test opposite directions.
I also did not test all possible combinations of fuses, so there are other ways in which my test was incomplete.
I place some confidence in my observations because they consistent with characterizations others have made of HiFi Tuning and Furutech fuses.
Cheers.

The HiFi Fuses are marked with diode symbols and, as I understand it, the direction of the diode “arrow” is random. So, you need to try both directions. The diode symbol is useful in knowing which way the fuse was oriented just before you changed directions.

For multiple fuses the only rational way to test for direction is start with one fuse, change direction and listen. Decide which direction sounds better, then move to the next fuse. After completely this test for all fuses repeat, in case you were uncertain about a fuse’s direction the first time around. As you proceed the sound will improve and make it easier to hear fuse directionality.

@geoffkait
Hey.
Flipped a fuse.
Ka-boom!
I flipped the fuse on the left inside rail. Perfection. Sound snapped into place. Before the edge of vocals were just a bit blurry. Very subtle difference. But difference between perfection and not.
Slim evidence on which to conclude changing the direction of the fuse was the cause.  A more convincing demo would have required flipping it back and back again to check if change in sound was specific to change in direction of fuse. And, experimenting with flipping other fuses. It is possible I had other fuses right and just this one wrong. Maybe I got lucky.
Regardless, I owe you thanks.
Very happy with sound. Not touching a thing.

Appreciate your knowledge. Enjoy your mischievious posts.

Rockin!