+1 Cundare2,
I replaced my stock power cords with Pangea AC9 MKII SE with Cardas copper (yeah I know they are above average at best) and heard no improvement. I later had 2 dedicated lines pulled and installed audiophile receptacles (Furutech GTX-D gold and rhodium) and Oyaide R1, and voila!.....now we're getting somewhere. Afterwards I went back to the OEM cables versus the Pangea cables, and now there was a sonic improvement.
My conclusion is that only when I upgraded my power delivered to the cable, was the cable able to produce a difference. As I am now building a dedicated listening room, the first thing I will include is 3 dedicated circuits.