if powercords change the things such a magnitude that you describe, it means something quite wrong with your setups!
Mert, The components Newly listed in his system are highly resolving as are those in my system (listed in the link above). Generally, the sonic differences between power cords is made more obvious in highly resolving systems.
Also, AC power is usually very contaminated by the appliances and switching devices in your home (and your neighbors' homes). Dedicated lines may reduce the ill effects but can't eliminate them. AC conditioners and filters help to further reduce the noise. Same is true for appropriately designed power cords such as the Elrod Statement Golds. In my case, the Golds reduced the AC noise significantly over and above what my AC re-generator was able to accomplish. Consequently, the signal to noise ratio was increased and all the glorious sonic benefits outlined in my review followed.

