The AV preamp has the hardest job of all audio-video components. As the hub and controller of a complex theater and music system it is expected to interact with nearly every component, provide a variety of audio and video processing functions all while being reliable and easy to use. This is no easy feat, especially in today's era of media servers, network and Internet streaming devices. If providing all of these features were not a difficult enough target to hit, keep in mind that it is a moving target. New formats and streaming services are introduced frequently and your AV processor is the component that needs to be able to interact with them.
Home Theater Review