What is an AV receiver?
An Audio/Video receiver is the hub of s home entertainment system. You connect all components - from sources such as a decoder, Blu-ray or DVD player, to loudspeakers and your television set - to it. When the Blu-ray player, for example, is selected, the AV receiver will send images to your TV and surround sound to your speakers.
The most important connections provided by an AV receiver include HDMI inputs that carry both high-definition video and audio signals. USB inputs allow the connection of external devices. Docking ports accommodate iDevices. There should also be provision for wired or wireless LAN, digital audio, and finally, analogue audio and video (component and composite) inputs for accommodating older players and decoders.
At the very least, you need to connect your AV receiver to a television. This is easy if you have a television with HDMI inputs. If your television doesn't have HDMI you'll need an AV receiver with component or composite video. Other useful outputs include Zone 2, LFE/subwoofer (the .1 channel in a 5.1 or 7.1 system), digital and analogue audio outputs.
How much power you need depends on how big you room is, how efficient your speakers are, how loud you want to listen. Unfortunately, there is no universal way of measuring power, so giving minimum power recommendation is difficult. An RMS power rating is generally the most reliable.
An AV receiver typically has at least five speaker outputs. These are for the trio of front speakers and the two surround speakers. Newer AV receivers will add surround back channels, but some can have as many as eleven speaker outputs: two surround back channels and up to four more front channels.
Ideally, you want an AV receiver that can read all the most important digital files from CD, DVD, media, Blu-ray and set-top boxes. These include Dolby and DTS decoding (and HD audio formats of these), MP3, FLAC, AAC AND WAV files.
If you own an AV receiver that has seven or more speaker outputs, but you only have five speakers, you can sometimes configure your receiver to use two amplifier channels per front speakers (just be sure that your speakers can be bi-amped). This can lead to better sound.
Another option often available on AV receivers is to use the unused channels to power speakers in another room. When this is done you could, for example, watch a movie in one room and listen to the radio (from the tuner in the receiver) in another. Zone 2 outputs are also usually available as a RCA outputs at the rear of the receiver.
Internet connectivity lets you connect to a home network, listen to internet radio, or even stream music stored on another computer that is also on your network.
This is closely related to point nine and requires a Wi-Fi connection. If you can often download an app for your receiver, control and configure it from your smart device, and even do so from another country, as long as the receiver is online.