Help selecting a power cord.


All my gear has the factory supplied power cords  I’m ready to try 1 aftermarket power cable as a test.  So what brand power cable should it be and what device gets it first?  Tube pre?  Tube main?  D/A?  CD transport?  Roon Nucleus?  Subs?  GE Trefs?? Turntable? Oppo 103?   Which piece of my gear should be most affected by the improved power cord??  I look forward to the responses and will likely choose the cord that has the most recommendations.
128x128fastninja12
I purchased a Furman it 20 I and diy five cords TOTL furutech rhodium and Furutech wall outlet, grounding plate and cover. Both amps plugged into the Furutech outlet on a dedicated circuit. Front end is on another outlet in use with the it 20 I, I couldn't be more happy and my system sounds better every day, several months on the cords and on the Furman.  I built a furutech speaker cable now too. I like furutech but now I'm broke.  Diy your own cords, several benefits to this approach and very easy. 
1) I won't add to brands as many have already made suggestions. I have a midlevel quality cord connected to a Furman ELITE-15 PF power conditioner but I cannot tell much difference. I've studied at the PS Audio power plant 12 (and talked with them on the phone at length) but am unsure and hesitant to spend $5K. 
2) one of my go-to audiophile friends hired an electrician and ran a dedicated line from his house panel to his stereo room. He said for a few hundred dollars, the result was amazing. Even his wife noticed the difference. 
3) I would love to hear what you end up with and if you can tell any improvements.

Good luck! 
Start with a quality hospital grade or better wall outlet, followed by power distribution (Furutech eTP-66). No need in the beginning to purchase a power conditioner. Allow yourself the ability to evaluate the sound of the power cords you are considering. Work one variable at a time.
I replaced the cord on a Nuforce STA-200 and the difference was huge! I replaced the cord on by Pass XA-25.. went back to the original factory cord!
The Cable Company might be a good place to start.
People suggest DIY. You can try for sure but I can almost guarantee that you will not succeed. It is incredibly difficult to build a cable that sounds like a 1k cable from reputable brand like Shunyata. Cables that are much better cost way over 5k and you will notice the difference immediately. Read this and pay special attention to the last post.

http://forum.audiogon.com/discussions/extra-extra-millercarbon-proven-wrong-read-all-about-it-extra-e?highlight=millercarbon&page=6

You can spend arm and leg on the cable as well but it is not likely going to be better than the one made professionally. Check here

http://forum.audiogon.com/discussions/nova-power-cord-model-m101-silver-review#2180479
“Cables that are much better cost way over 5k and you will notice the difference immediately”

@begow,
I respectfully disagree with above statement. There are plenty of professionally made high quality power cords to choose from that can sound incredibly good under $1K. As with any aftermarket cable, the degree of improvement one hears is system dependent.