MihornThat includes fuses in > 30~40 years old vintage gears. Switching the direction of the fuse, the electrical current takes longer time (and subtle) to hear the effect because many active parts have to react to the change of new current (unlike audio signal). In my experience, it usually took 1~10 minutes to hear.
the direction of metal cable is physically made and the sound doesn't change with the length of time. I heard sounds of many 40-50 years old metal wires in vintage gears melts like butter (in sound) in 1~2 minutes.
To hear the effect of switching the direction of a fuse and wires clearly, one
needs pretty revealing and transparent sounding system. My sound system
consists more (not all) correct direction cables from a source to speakers since I
make my own power cords, speaker and IC cables. Also, I make my own speakers.
In my sound set up, I even hear the effect of different power cords very clear
that the power cord influences the sound like a interconnect cable. There was a
power cord shoot-out 2 months ago at my shop among Verastarr Grand Illusion AC Power Cords, acustic zen absolute power cord, Synergistic Research Power Cords. They are $2K range. VG was clearer (more silver??)
but had a peak around 3k hz. AZ was well balanced and bit less clear than
VG. SR had wrong direction wires and was bad sounding. I liked AZ best. I hope SR’s
mistake (wrong direction) is only for this sample we tested.
Alex/Wavetouch Audio

