Do powercords make a difference in sound?

Yes.
I never thought it could make a difference untill I tried one in my system. I now have after market power cords on all my equipment, and yes I'm crazy and like to try almost every tweak that I hear about, but if you add up all the little tweaks one does to their system it starts to make a big difference
Sometimes a huge difference sometime small.
Noticed a big improvment on power amps the most.
Joe

About 10 years ago I did not believe that a power cord could make a difference. Did not make any sense to me at all.
I saw that a online audio store was having a sale on the older version of the PS Audio power cables. The price was hard to beat. For less than $75.00 I bought a cable to see what all the hype was about.
To my ears, on my system I could hear an improvement. I used the cable on my amps.
I would suggest that you buy a power cable, used or on sale, and try it in your system. You only need to buy one to try, you do not have to spend a lot of money.
If you hear or think you hear an improvement that will be the only test or opinion that you need. If you do not hear an improvement, then you know for sure what your ears are telling you.
If you were to have a pair of mono amps, just get one cable and put the cable on only one of the amps and give a listen.
For under a $100.00 you can find out for yourself if it is hype or a reality.
Respectfully,
Joe Nies