Best power cord for a preamp?

The stock powercord

plugged into the proper power conditioner

@slaw . Lack of noise. Fast power delivery. Lowest noise will allow detail, nuance, (dynamics- as lowest sounds heard)  :)  . 

Seems impossible to figure out man 

Top-tier power cords are the best way to tweak a state-of-the-art system for maximum realism and definition. After tube rolling, cable selection and matching, suspension tuning, final equipment selections, speaker adjustments, and room acoustics, you may not quite have that timbral naturalness and background blackness that brings the system to life. For that final adjustment, try different power cords to bring out those important nuances”.

If you can read S… like this and still have the ‘audiophile’ urge to waste money there is professional health help available.

It took while for me to figure out that the first half was a quote. 😙

Getting a recommendation from the preamp or amp manufacturer can be helpful.
Generally they either laugh.
Or they do not comment.

Of course for the equipment we have both heard, it does have a power supply which was not a freebie.

Lack of noise. Fast power delivery. Lowest noise will allow detail, nuance, (dynamics- as lowest sounds heard)  :)  

Why particularly the preamp, have you solved the power amp cable?

Just changing the preamp's power cable alone will not bring the upgrades you are looking for. 

My suggestion is borrowing a set, for both power and pre, from a dealer and listen how it goes, if you like the change decide if you want to spend more or less.