Sorry to say - but if your house's electrical network is not up to standard it won't help using expensive power cables. Rather upgrade your interconnects or someting else...
I'd use the Harmonix on cdp and pre-amp.
Power cords do make a difference on power amps but I would think you would get most benefit on the first two links of the chain, so to speak.
Since you don't mention the make of the SET amps?
best ask advice from people who have the amps you intend
using re the best power cords for them.