Warm sounding power cord for for CD player to suppress digital glare on vocals.

" I listen to older CDs (and the Bealtes) and there is definitely some glare in vocals on many of these recordings "

...:Powercord??
Is that too much of a whole bunch to ask just from powercord? 
How powercord even $$$$ can fix THAT?
I've just imagined anyone casual reading that LOL.

For older CDs all you need is tube buffer such as Musical Fidelity that will cost substantially lower than so mentioned powercord.

The only-only solution is to purchase better quality disk. Other than that you can take half-pint of whiskey and listen again and figure it isn't that bad after all.