Yes, according to my ears.
I have a Modwright 999ES that has a separate power supply.
I find I get the biggest changes when I switch cords
on the power supply. You will get a change on the player
side but its not as dramatic as on the power supply IMO.
I'm currently using the Tek Line Reference cord on my
power supply and player side and prefer this combo
to the two Purist Audio Dominus cords I was using