Re: Furman Power Conditioner
They clean line noise off your mains power supply (the stuff from the wall) so that they don't contaminate your amp.
(For an example of noise on your power line, go run your vacuum cleaner while watching tv).
They also act as top notch surge protectors, have overvoltage protection, some have voltage/amperage meters, act as a power bar, and help to eliminate ground loops.