I did this experiment:
1. borrowed very high end power cords - significant difference - but not as much as spending the $10K on the pre, the amp, or anything else
2. installed isolation transformer to run separate outlets at 20% of above cost
3. plugged factory power cords into isolated outlets - sounded better than expensive cords into normal outlets (1)
4. plugged expensive cords into isolated outlets - no different than (3).
Experiment proved that in my case, an isolation transformer worked better than expensive power cords, for much less money, and expensive power cords brought NO improvement after the isolation transformer cleaned up the power.
For context, I live half a mile from the nearest commercial user, five miles from the nearest industrial user.
This experiment contradicts the strong opinions of our resident armchair "experts". Use the information as you see fit.
Good luck.