An audio receiver only collects audio and sends it to your speakers. Your can connect multiple devices, but you'll need multiple video inputs on your TV in order to switch between a DVR, VCR or DVD player. Audio-only receivers usually only provide stereo audio. While they are well suited for music or for using external speakers with your TV, they don't provide you with surround sound audio contained on DVDs.

A surround sound receiver adds video connections to the mix. You can use the receiver to switch both the video and audio so you don't have to change the input on your TV. A/V devices run into the receiver and the audio goes out to the speakers while the video goes out to your TV. However, these devices do not have digital audio connections, to they don't produce Dolby Digital 5.1 surround sound. They use another Dolby format, known as Pro Logic. While this format does make use of surround speakers, they aren't separate. The surround speakers produce identical audio, which reduces the surround sound effect. These units are becoming more rare with Dolby Digital receivers becoming more affordable. At this point, the price difference is so little, you may as well go with a Dolby Digital receiver.

A Dolby Digital receiver adds digital audio connections that allow more channels of audio to be transmitted. These units commonly produce up to 5 audio channels along with a single subwoofer (known as 5.1). This allows for a center channel for most speech, left and right front speakers for most music and sounds that come from the left or right, rear left and right surround speakers that provide bits of fill audio (such as bullet ricochets) that occurs toward the rear of the soundscape. Unlike Pro Logic, Dolby Digital rear speakers work independantly of each other (known as discrete audio) so different sounds can be heard in each speaker. In addition to 5.1 surround, some digital receivers can produce even more audio channels, though not many audio sources contain that many. For example, you might see a receiver that produces 6.1 (which adds a rear center channel), 6.2 (which adds a second subwoofer) or even more channels.

In the world of receivers, you often do get what you pay for. Generally, the higher end receivers will have more available inputs and outputs. More inputs mean more devices can be connected. More outputs mean you can send audio to addition devices or areas of your home (for example, you could send relaxing music into the dining room during dinner). Some receivers even have dual channel capabilities that allow two different audio sources to be send to different places at the same time. For example, you could watch a DVD in the living room while your spouse listens to music while working on the computer in the Den.

In addition to more inputs and outputs, bigher end receivers often have better quality connections. They tend to include component or even DVI connections, rather than the normal composite (RCA) or S-Video connections.

Finally, high end units tend to have highly adaptable remote controls that can be customized to work with all your equipment. The can be programmed to turn on and switch to multiple devices (such as the TV, a DVD player and the receiver itself) with the press of a single button. These remotes are often radio frequency (RF) units that don't even need to be in the same room to work. This is useful if you are listening to music in another room.