Which power cord should you buy first

FWIW, a Shunyata Venom V14 power cable (not the V14 Digital) at about $100 used and $200 might be a good power cable for experimenting as it didn't seem to have any dramatically bad effects in any part of my system as did some more expensive power cables. Get one of those and a generic power cable from Home Depot and you have everything you need to hear what effect a power cable might have in different parts of your system.

I bought 10 awg shielded power cable for my power amp first and, gradually, 12 awg or 14 awg shielded cables for the rest of the gears. My Monster power conditioner has a pretty beefy shielded cable so I don’t worry about it.

stock one is technically used first.

When I first started, I bought the Amp power cable first. As my system evolved, I Introduced a Saturn Audio 103C power conditioner, and an isolated 20 amp CCT. that power cord from the wall to the PC was critical. then everything plugged into the PC. I purchased a cable for every component after that.

Dac , power cord  the dac being the source provides the music coming in you want this at its best for you cannot correct it down stream .