Any experience converting 2 prong ac to power cord

I've got a Carver tfm 42 amp as well as marantz ma500 amp that I am cosidering changing from 2 prong to quality power cords. Does anyone have suggestions if worth it. I like the Carver alot. It runs my main polk audio 12s. I just moved to an apartment and have had all kinds of problems with more hum & buzz in my system. I thougt I'd start with a couple hundred dollar used line conditioner for the cd and preamp but am wondering if I can go with power cords to help also.