I know I will get shit on for this but yeah they can. I totally did not want to believe it either and laughed at the thought of a fkn boutique power cable. Then the owner of the local shop I go to asked me to come hear a difference and to bring my own amp in. So I did and in his sound proof amp room we tried my normal vs his analysis plug cable and I couldn't believe I could hear a difference. My butterslax sounded just fuller and defined. But this was in a quiet amp room A/B in power cables sitting in front of the speaker, in a live situation with a band, nobody is going to fkn know lol. I ended up buying a cable only because my thing is direct recording, and every bit of noise and interference I can reduce is worth it for myself.