Never used Signal Cable, but I own 3 Cullen Crossover cables, obviously I found them to be good performers.
I have tried 5 different power cord brands (nothing overly expensive), two of them I didn't like (way to warm in my system), when I decided to try a Silnote Audio Poseidon ES power cord I was surprised how much it improved my system. After using the Silnote for a while I decided to buy a second one.
I use one Silnote cord on my integrated amp and the other on my phono stage, other equipment using my other cords. I have found power cords to make a profound difference on my systems performance.
Gary