What was the first power cable that you noticed a difference in the sound?

when i used power cord, i was able to power it up and get sound and when i disconnected it, i really heard no sound. that's how i first time heard differences.

Well I had a system  that just didn't  play bass I changed  the receptacle s to the 20 amp lines to the amps. Wow I got a bunch of bass. I am wondering  if you cannot tell much difference  because  you have a problem  farther up the line. If you don't want to spend to much money  try a hospital  grade plug. You can hear the difference  between  the plating on the receptacle s as well I have both gold and rhodium  receptacle s. Try cords from a friend or try cords that you can audition  and return. 

Regards

My experience supports what Jerry is saying. With some amps I have heard a noticeable difference upgrading the stock cord to an aftermarket model—not a huge difference but one “worth” investing some additional coin. However, an amp with a well designed power supply seems not to care about PCs. For example, I ran 4 different cables on my David Berning designed LTA UL+ amps and heard no difference from the stock cord. FYI power supply design is David’s forte and, when his power supply designs are mated with his ZOTL circuitry you end up with a great amp that doesn’t need an expensive PC.