I just got my Signal Cable Magicpower today, and even though it's made from pretty stock stuff (Carol 10/3 and Marinco) im very impressed with it so far.. actually im pretty floored, my Headphone amp is in the shop at hte moment, getting an upgrade, so I hooked it up to my Promedia 5.1's and wow (Previously used Volex 17604) the bass is deeper then i've EVER heard these things go, and the high's are much more refined and clearer.. im pretty shocked, can't wait to try it out on my headphone amp.. im a beleiver in power cords now for sure, the differnce is signifigant. I think what Mark says is true though, it depends alot on your gear, it stands to reason that if you have 10k amps they probably have a massive, high quality built in power supply so cords will make less of a differnce, that might explain why the above fellow can't hear much of a differnce.. 16k amp.. has to have insane power supply. It's also subjective a big differnce to me might not be large to someone else, though I can't understand how someone would call what im hearing right now small by any stretch. And these speakers suck I wouldent be surprized if they could best a stock Promedia Ultra setup with this cord..
Edit: I was thinking of building more of these carol 10/3 cords and realized just how great a deal it actually is from signal cable. The cost is about 35$ to build one, and sells for 59$. Anyone know a place to buy carol 10/3 by the foot instead of spools, I can only find it in 25 foot spools, which cost 30$. This cable is a bargain, really in a different league then the Volex it replaced (all the benefits, without the rolled off highs and lows)