Nothing wrong with a bit of positive placebo (if it is placebo that is)
Get someone to switch them without you seeing. Then see if you can guess. If you guess correctly, maybe you're onto something.
If they are brightly coloured, then their background will appear darker.
Hey, don't mind me, I'm deaf anyway.
Which ones did you get? I picked up some Pangea power cables a few years ago when they went on ultra cheap closeout. Like you, I think they made a very slight difference with the black background. For under $50, I think they were a decent deal. I wouldn't pay more for a comparable improvement.
@crazychile got 2 of these https://www.amazon.com/dp/B01L2MBYWC/ref=cm_sw_em_r_mt_dp_U_VVZPDbJC3VX7N connected to a power conditioner
Separate names with a comma.