A device intended for use with hi-fi products that "conditions" the electric power signal in order to make your existing system sound better or in the case of transistor amps to be more efficient. This is archived typically through the use of active or passive filtering but more exotic variants exist. This type of device is increasingly popular in countries such as the USA were we see more variations in the quality and age of electrical installations and infrastructure than we typically see in other western countries and in the UK were standards and work practices in electrical wiring date back to the stone age, but theoretically a conditioner (depending on design) should offer at the least a minimal benefit to any system regardless. We first see these units in used in the medical sector were they were used to shield very sensitive equipment from minor variations in input voltages and shapes but those devised leaked into the hi-fi world in the 80's. You should not confuse them with battery based power back-up devices, these have an electrical output that is not sinusoidal which may cause trouble with audio equipment with linear power supplies, in particular with amplifiers since the further away from a pure sinus wave the power signal is the less efficient the amplifier becomes. There do exist however battery based power conditioners that mix rechargeable battery technology with more normal filtering techniques to create ultra pure sinus waves, these are rare and expensive however. Alternativly : A device expressively designed to con nonplussed audiophiles out of money.

This definition is in context to Audio Technology. See more contextual defintions for Power Conditioner.