Where do cables upgrades have the most impact?


Assuming all existing cables in a system are atleast mid-grade (not junk), which cables/interconnects should be upgrade first and in what order? Where should one start?
128x1281extreme
Curious if those saying the power cable had the most impact are plugging into a power conditioner or a wall outlet?
For the impact of aftermarket power cables, The wall or conditioner.. Does not matter. Power cords can be effective from/to either. Plus consider the wall AC duplex in this equation. The AC duplex can also have an effect on the sound (specially if aftermarket powercords are used)