AV receivers are regarded as the central hub of a 5.1 home cinema system - it takes inputs via HDMI cables from the sources in your system (Blu-ray, DVD, Sky, Playstation 3 , Apple TV etc) and switches and scales the video so that you get the best possible picture quality. The HDMI output of the HDMI AV Amplifier ( also known as HDMI amplifier, 5.1 AV amplifier or AV amps) is then connected via HDMI cable to your flat panel Television or Home Cinema Projector.
Meanwhile, the AV receiver strips off the audio data from the HDMI feed and decodes it either by internal HD processing (DTS Master HD or Dolby True HD) or one of the many standard decoding codecs. These 5.1surround sound audio channels are then sent to a multichannel power amplifier within the AV Receiver to drive your loudspeakers. Additional features often include a radio tuner with AM/FM and DAB, network streaming of music and media via ethernet, multiple audio and video zones, and remote control via iPhone or iPod.
The vast majority of 5.1 amplifiers also have an extra two channels which can be used in a number of ways - either add an extra pair of surround back speakers to give a more immersive surround sound experience, or re-assign the two channels to bi-amp your front left and right speakers for better stereo performance, or create a zone 2 in another room for stereo music, connected to a suitable pair of loudspeakers.
A setup microphone is often provided with AV amps to allow you to automatically calibrate the level and distance of each of the 5.1 surround speakers, so that at the main listening positions you experience the best possible sound experience.
For music listening in stereo, most AV receivers have a 'Pure Direct' funtion which disables all of the video and sound decoding circuitry to allow the purest stereo audio path possible. Analogue audio sources such as hi-fi turntable, CD player, radio tuner are connected to the left and right analog audio inputs via audio interconnects.
When thinking of AV furniture or hifi racks to house your AV Receiver, remember to allow at least a 50mm gap between the top of the AV receiver and the shelf above, to allow the heat generated internally to escape. Also check the depth of the receiver and remember to add 50mm to allow cables to connect and protrude from the rear of the amplifier.
For a comprehensive guide to choosing an AV receiver read our article on our blog.