While most equate home theatre setups with hi-def tellies and lounges bulging with massive speakers, the beating heart of any home theatre is a capable AV receiver.
Essentially an amplifier on steroids, AV receivers decode the surround audio encoded into DVDs or Blu-ray's movies, Freeview and Sky Digital TV to deliver you an all singing, all dancing on-sofa cinematic experience.
Choosing from the nearly endless array of AV receiver brands and models however can involve wading through an astonishing collection of heavy specs that can all but boggle the most hardened AV fanatic or rocket scientist.
Feeling the pain of many a frustrated AV component buyer, I've attempting to translate some of these into plain English to give you the good oil on what to look for when buying an AV receiver.
Surround Formats
If you're wondering what could possibly be so complex about buying a home theatre amp, take the number of surround sound formats on offer for instance. Buying an AV receiver that supports Dolby Digital, Dolby Pro-Logic and DTS formats is the basic must-have for getting surround audio.
Extended formats such as Dolby Digital EX and DTS ES will also deliver surround audio to seven rather than five speakers plus a subwoofer, while Tru-HD lets you reap the sonic benefits of Blu-ray movies.
Add to this the umpteen bazillion manufacturer specific surround modes (which are usually called inventive names like auditorium, hall, cathedral and stadium etc) that are also bundled with most AV receivers and there's fertile ground for confusion, not to mention a need for aspirin.
If all these surround settings bake your noodle, don't fret, just follow this simple rule: keep it simple and don't be afraid to ask questions if unsure when buying. Most AV receivers nowadays support all the surround formats needed to play DVDs (such as Dolby Digital or DTS etc.) and most will automatically detect which surround format needs to be decoded from the DVD player. Surround modes aren't surround formats, but digital processing modes designed to re-create a simulated version of real-life venues. In reality they're often hardly used so can usually be ignored.
How much power?
When it comes to the amount of power an amp can deliver power, common wisdom has long had it that getting as much wattage as you can afford is a good thing. In reality, the power ratings quoted by different manufacturers can vary widely as manufacturers tend to use differing measurement methods when quoting the power output of their equipment. This means that a 120 watt per channel model from one brand might have a similar output to a 140 watt model from another manufacturer. Equally important is the room size, as is the type, impedance and the number of speakers you'll use with the receiver as these will affect how powerful a home theatre receiver you'll need.
If you're incorporating an existing set of speakers into your home cinema, check their specs, noting their power ratings (in watts RMS preferably) and impendence (in Ohms or ?).
Ideally an amp shouldn't drive a speaker beyond its rated power limits whilst low impendence speakers will require more power in order to perform. If unsure, run your speaker specs past the amp retailer to make sure you're getting enough grunt, but not so much that you shred your speakers when the volume's turned up.
Connections
As the audio and video widgets in your cabinet ultimately do their thing through your AV receiver, making sure you've got the right amount and right type of connections for them (plus spares for future expansion) is a must.
At the very minimum you'll probably need to hook up an HD capable TV, a CD/DVD player plus VCR or PVR/MySky box. Chances are you'll also want to hook up a few extras such as a games console, media centre PC, Apple TV or gadgets such as a camcorder, digital camera, or iPod/MP3 player. Check that there are enough spare inputs on the back; and for gadgets you want to connect on an ad-hoc basis, take a closer look at the front panel inputs to make sure they match your requirements.
Where possible use digital inputs such as HDMI, SPIDF and coaxial connections as these will minimise degradation between their source and your AV receiver. HDMI inputs are the best for connecting digital sources such as HDTV receivers, DVD players and PVRs to the receiver, and they have the added benefit of delivering both audio and video over a single cable, minimising clutter. If your device only supports analogue video, aim for component video (red, blue and green RCA plugs), or failing that S-Video. Where there's no other choice, make sure you AV receiver supports composite video (red, white and yellow RCAs). Newer AV receivers are more often than not also digital media savvy, incorporating a USB or ethernet network port for the streaming of music and video files.
Other key considerations
Connections, power and surround support may be the biggies to look out for, but they're by no means the only things to take into account. Making sure you can live with the receiver's usability is a biggie. Is its remote logically laid out and is it easy to drive? Can you work it in a movie-dark room without having to get up and put a light on?
When choosing an AV amp, ask to have a brief play with its remote. Another trap easily overlooked by first time buyers is the simplicity of initial setup, calibration and potential tweakability. While many AV receivers nowadays come bundled with a calibration microphone and can automatically configure themselves, more often than not manual tuning is still needed. This means easy access to audio parameters such as speaker levels, distances and equalisation also makes a big difference.
Another nifty trick is multi-zone output which allows you to hook up an extra set of speakers to play different tunes in multiple rooms. This is great if for instance, you've got kids who want to hear their own music. Some AV amps can also do up-conversion. Using built-in video processing hardware, up-conversion capable AV receivers can take a standard definition image and process it into faux HD, which is a great way of making standard def DVDs or game console output look considerably better.
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