Which power cord to upgrade first?

None,

1. add a dedicated line first.

2. Upgrade the electrical outlet.

3. Now upgrade your power cord.

Tvad, $5 cord? that's cool, but I said "basically". And the better power cord in your case was the $5 cord for that particular component.
It's a combination of things. Not necessarily one upgraded cord is going to make a huge improvement. Have you thought about what the rest of the power cords in your system are doing? Is it possible that all the other cords there in your system did more harm than good in the combination with your pre-amp and then you drop this el-cheapo cord that in the context of another system would probably sound like crap. And all of a sudden things come to life?
I appreciate what you're saying, but the most important thing is system synergy. You achieved it with the addition of that $5 cord. Congrats. :)

04-14-06: Audphile1
Tvad, $5 cord? that's cool, but I said "basically". And the
better power cord in your case was the $5 cord for that particular
component

Exactly. I wanted to edit my
statement to reflect this, but alas I was too late.

I'm with you on the point of synergy. If you read some of my past posts
you will see that I mention synergy time and time again, which is why
experimentation with placement of power cords and other tweaks is so
important. Believe me, my power cords have been shifted in every
conceivable way, and they now rest in their most optimal locations...and
all are better than stock cords.

Pick up a Volex from Carleton-Bates.com and try one. There are many
here who are trying them, and several have been converted!

(BTW, I want to give credit to Dusty Vawter of CI Audio, who introduced
me to Volex cords many months ago.)

I always put the PC on the cdp first....amp thereafter but amp pc effect was subtle and the cdp was not.

Larry

Tvad, your suggestion comes right on time. I need a cheap cord now while I am waiting for my Audience cords to arrive. I have all the stock cords burried somewhere in the closet and I'm too lazy to dig in there for them.
I may consider the Volex.