Power cables best home?

I have access to two highend power cables, and I'm wondering which componets will benefit the most from their use? I'm considering using one for my 5ch amp and the other for my preamp. What improvments can I look forward to by going this rout?

Thanks for your insight.
The CD player is a good choice. The Amp either second, or it you have a IEC connection of a power strip or conditioner. The cord on a power strip/conditioner will affect everything plugged into it. I also found a big improvement upgrading the cord on my REL sub.
Always work the chain from the front end down, transport/dac or cd player first, preamp second, and amp last. This goes for upgrading cables or installing isolation devices as well...i.e.(cones,shelves,platforms) follow the signal, source to the output. Good luck!
When I want to hear the sonic signature of a specific AC cable, I change all my AC cords back to stock & then install the "test" cable on my preamp. Bob Cohen at Fatwyre.com (Cable Co) advised my to try that approach long ago & it seems to work very well. So after the preamp is 'tuned' appropriately then go the the source component (one box CD player, or DAC, or the phono stage for an analog rig) & tune that component with the AC cord of your liking. Tune the power amp last, because if you do that piece first instead then all of your tuning work on the front end will also be affected
Do it on a Sunday when you have lots of time. Try the digital end first (DVD/CD, processor), then try your old power cords. Then do the same for you amp. I believe you'll notice a bigger difference on the digital end. Knowing us tweakers, you'll probably end up buying more powercords so all the equipment can have them.