There is a third option of cutting the existing power cable off reasonably close to the unit and wiring on an IEC connector.
Are you handy w/a dremel tool? Do you feel confident cuting out an opening for a chassis mount IEC plug using a grinding disk attachment? This will give the best sonic results but you have to know what you doing and have to be very careful. It does not have to be mounted where your existing cord is. Use silver-bearing solder and be sure you do not get any dust inside your CDP. Is your stock cord 18ga? IF IT IS, change it out to 16ga. wire. If it is 16 ga. leave it alone unless you're able and willing to install an IEC chassis mount plug. Finally, add a ferrite clamp magnet to the cord inside the chassis. It will most likely improve the sound. (The new Marantz CD-5003 CDP uses 2 clamp magnets and 2 round ferrite magnets. It came stock this way! (At least mine did.) VERY impressive build quality considering its $349 retail price. I did changed out the C7 IEC plug to a regular IEC Furatech plug after trying an C7 adaptor IEC plug which didn't make any real improvement. The Furatech IEC plug made a hugh improvement in sound quality. What was Marantz thinking of?) I hope this helps. Bill
But by running current through some of the old power cord, wouldn't that defeat the purpose using of a better one?it will still work fine even with the pigtail. If you like the results (and you may wish to experiment with different upgrade cords to determine your preferred sonic signature) then later you can add the IEC, or have a local shop do that for you. Greenlee makes a special chassis punch for just such a purpose. Or you may be able to use a nibbling tool. The Dremel grinding option; I would not advise doing that due to the particles & metal dust which gets into everything & can cause serious damage. The ferrite may or may not be desirable; try it both ways if you try it at all; it will affect your sound. Some cords are already filtered anyway.