The answer to this question depends upon where the lines are comming from, and the 'quality' back at the service connection. If you have clean power to the hi-fi,(from the service connection) separating out the feeds to the amps won't necessarily improve the situation. If your existing lines are a source of noise, from RFI and grounding problems, then new feeds will help, though the front end will benifit more than the amps.
Good luck
Good luck