You should not need a power conditioner to prevent hum. Typically hum is caused by a ground loop. Often it is a result of connecting cable TV into your system or plugging into outlets that have different ground potentials for some reason.
The easy troublshooting tips are:
1. disconnect cable TV or satellite Coax from your system.
2. connect your entire system into the same quad/dual outlet using a power strip.
If either of these activities resolve the hum issue, you know the problem is a ground loop and you can work to resolve it. If it's the coax, place a ground loop isolator in line. There are many available including one from radio shack, a jensen unit and the magic block from Mondial. They range in price from a few bucks to about $90 for the Mondial. If connecting all of the components into the same outlet solves the problem, you have an electrical system grounding issue which can be resolved by an electricial.
Lifting the ground on one or more of the components could also resolve the issue.
TIC