I'd say have your significant other (if you have one) or friend install the fuse(s) so that you can't see them, play your favorite tune, then have the same person (for continuity) reverse it, again without you seeing it, play the same tune and realize there is no difference and you wasted your money.
Fuse Direction for Pass Labs Amp and Preamp
I am going to re fuse my Pass X250.8 and XP-32 with Synergistic Research purple fuses in a couple of days. I was hoping to get advice on a rule of thumb for direction of the fuses. My instinct tells me to start by installing the fuse by the direction of the lettering on the fuses. I am thinking that the direction should be the lettering left to right with the beginning of the lettering facing out of the amp and the end of the lettering facing into the amp. Does this sound right?