I think you'll find that good power cords do not actually make your system sound brighter, but allows your amp(s) to perform better.
Since the power side of the amp is completely isolated from the signal side
However: providing a good supply will allow peaks to be processed by the amps - resulting in a "different" sound.
With a better supply you should also have noticed a distinct improvement in the bass reproduction? - i.e. tighter, deeper and more dynamic
If you didn't, then I would look into the speaker cables. If they are not of sufficient gauge (like 10 gauge) or the capacitance is too high, this would impact the performance of the amp and result in unnatural sound
Another place to look if the sound is overly bright may be the interconnects, where, if the capacitance in them is too high, the interconnect acts as a filter, enhancing the highs and restricting the bass.
NOTE:
1. some amps take a distinct dislike to high capacitance speaker cables
2. phono cart's definitely do not like high capacitance interconnects
Start with the interconnects and move on to the speaker cables
Looking at the Pangea design they seem to offer extremely good bang for the buck, since they are a very similar design to the cables I have on my system, but I have not tried them.
