You're going to have to try some new cables to find out.
I like SR's stuff, but have had good results with the higher-end GR power cables, too. (The GR cable took FOREVER to break in, so bear that in mind...).
Older Power Cables
In my current system, I have three older moderately expensive power cables: 2 from PS Audio purchased about 24 years ago for $600 used and one MIT Zip Cord II purchased new. I was just wondering what will differences will I likely be able to "hear" by replacing them with some of the newer power cords that is currently being market.