An AV receiver is the hub of any home-theatre system. Its job is to take the sound and video information from your DVD, CD player or set-top-box and, if necessary, convert it to an appropriate output - then send it through to your screen and speakers.

When you buy a 'home theatre in a box' the AV receiver and DVD/CD player are often combined into one unit, which you connect to the speakers and TV. However, there are two good reasons to buy separate components: you get more control over the quality of each and, should one component break down, you don't have to replace the whole system. The former is by far the most important.

Not just Sony

We picked four Sony models from different sectors of the market to illustrate what you can expect for your money. There are of course many other brands in the market which could have a model that suits your needs better than our examples. It's worth spending the time to compare specifications. Other brands include:

• Denon
• Harmon Kardon
• JVC
• Kenwood
• Marantz
• Onkyo
• Panasonic
• Pioneer
• Rotel
• Yamaha

Sound quality

The main purpose of a home theatre set-up is to provide surround sound. The AV receiver includes the amplifiers necessary to drive your speakers. At the cheaper end you're likely to get a 5.1 system, which means it has five speaker connections (three front and two back) and a sub-woofer connection. This is the most common format for DVD movies.

More expensive systems tend to be 6.1, with three at the front, two back and one back centre, or 7.1, which has an extra back centre speaker. You don't necessarily get better sound with a 6.1 or 7.1. Their aim is to try to increase the sensation of sounds coming from different directions by using more speakers, as you'd expect in a movie theatre.

Read the complete buying guide plus the Choice Verdict