I have done both (matched IC and power cord and mismatched). I find a subtle improvement when matched when using products of similar quality. I would only focus on this if it were the weakest link in my system, otherwise not that much of a difference to stress.
Unmatched power cords
I discovered recently to my amazement that I had two mismatched Interconnects from my preamp to my amp. One is a Morrow (which cables I use to connect most of my system) and the other is a Cardas. I don’t know how long they’ve been there, but the sound has been great all along.
I’m wondering it would be wise to match one or the other, or go with “if it ain’t broke don’t fix it.”