shielded vs non-shielded pc for amp

The owner's manual for my Carver Lightstar Reference states
in bold print that they DO NOT recommend the replacement of the original power cords with any others. The reason being that the specially designed shielding is an integral part of the AC line conditioning and filtering. (The amp has a built in line conditioner). I've moved my equipment rack and the original cords do not reach the outlets.

(1) Need I replace with shielded only?
(2) Since the amp is dual-mono (300wpc) and can draw upwards of 16amps/channel (according to the manual), I'll be using two different circuits which are different distances to the amp. Will I hear a difference if one leg is 10 ft longer than the other? Thanks for your thoughts