Everything matters. Full stop. Read reviews and pick a PC that exhibits the sound characteristics that would combine well for your system/tastes. Buy used and you’ll save a bundle, and if you buy wisely you can turn around and sell it for little/no loss if for some reason they don’t work out and just repeat the process til you find “the one.”
A couple other meaningful and cost-effective upgrades would be to pick up something like a used Audience AR1p power conditioner that come up used on hifishark every month or so for only around $250. Using that to feed your Wiremold will effectively give your whole system very good power conditioning for a song (this is what I did BTW and also use a Wiremold power strip). Last, upgrading the wall outlet can also make a nice improvement for relatively very little cost. Here’s a good one to consider…
https://www.cruzefirstaudio.com/maestro/the-maestro-outlet
Hope this helps, and best of luck.