My Von Schweikert VR9 SE Mk2 have powered subs built-in. Yes, A/C cables provide the power from a traditional/common power outlet and source. I am not going to open up the amp to play with a 1000 watt amp fuse to find out which direction sounds better below 50 or 60 Hz or lower. I'm lazy. If you are referring to my speaker cable from the amps, I assume it is bidirectional. While the speaker wires originate possibly with similar bidirectional characteristics initially, after burn-in they probably adopt directionality. I just know that the many fuses sound different initially and with burn-in. Too obvious with Acme, Hi-Fi Tuning and Synergistic Research fuses my friends and I have used.Is the current to your speakers A/C? Is A/C directional ? If the fuse is between the cable doesn't the current move in both directions.
My Lampizator Poseidon manufacturer specifically states NOT to play with the fuse, that it was chosen/used for it's protection and boutique fuses could be dangerous to the unit's health which in my case is $25,000 investment. I'm going to abide by the manufacturer wishes. For all my prior DACs, amps and pre-amps, etc. I did change the fuses as the supplied glass or ceramic fuses were junk (sonically).