This section includes both replacement power supplies (to replace missing or faulty units) and power supply upgrades. Many hi-fi manufacturers now make a dedicated or specific power supply unit as an upgrade to an existing model. Each of these is designed to realise even better performance by virtue of the fact its often a more substantial design in a dedicated enclosure that delivers a purer power supply to your system. This follows the logic that as the energy that enters your system in power eventually becomes the sound that you hear, the better quality the power supply, the better quality the sound. In practice, many of the power supply upgrades can make a significant difference.