really inexpensive power cords

good choice opting out of the PS Audio cables, they can be greatly bettered. VH Audio makes some fantastic power cables that are very reasonably priced. Upgrading to premium Wattgate or Furutech connectors is a serious step upwards as well.

I've had good experience with Signal Cable, with all 3 grades of Frank's power cords for everything in my system ... basic, digital, and premium with silver. Worth checking out.

Jalapenos is right about VenHaus (VH) I used their formula to make some terrific PCs for about $50 apiece. An respected Agoner compared this self made product with PCs in the $500 range and preferred the VH. They made an immediate improvement in my stereo being much more open than the stock cords.

Why do you want to upgrade the PC's in your second system?
Do you listen critically or just for background music? If for background, buy some music instead. If you're going to do some critical listening, start w/some DIY, using Chris VH or Bob Crump recipes, then see if you want to head further down the road. You can even do something like get upgraded AC ends and use Carol cable for an improvement over stock. It takes a little experimenting w/your system to see if it's a viable option.

Don't forget the basics before you start on a PC quest. Make sure your room is optimized w/regards to spkr placement and taming reflections.

Also, even if you don't upgrade your PC's, I would suggest swapping out your AC outlets for something else. Pretty much any upgrade in this area will make a difference & you don't need to spend big bucks to hear a change. My favorites are Oyaide and Furutech. Look at the VH Audio website for more details.