New Power Cable on a 1990 Hafler DH120?

The sound of an electronic component starts with its power supply. NOT with the wire connecting it to the AC outlet. If you believe otherwise then I recommend joining the Flat Earth Society.

If you want to experiment buy an IEC outlet. Cut off most of the old power cord, leaving several inches. Strip the two conductor ends. Attach each copper conductor to a screw terminal on the back of the IEC outlet. Now you can use any power cord with a male IEC connector. 

@carlsbad : those old Hafler SS amps/preamps were made before IEC outlets were in common use. I have a Hafler 220/110 pair - both with captive AC cords.