The AV (Audio Video) receiver is the main device that you will use to connect all of your home theater components. Therefore, it is important to go for a high-end, more sophisticated device in order to prevent signal losses by the receiver and to be prepared for more connections in the future.
Currently, it is important to have as many digital connections on the AV receiver as possible. If you have or plan to have a flat TV or a digital display in your home theater setup, do not go for any AV receiver which does not have HDMI output and input. In addition, consider TOSLINK, S/PDIF audio connections as “mandatory" and do not settle for less.
Plus, to take advantage of the various sound effects in DVDs, High Definition content and games, your receiver needs to have Dolby and DTS technologies. Dolby Digital is the most common feature in AV receivers, but there are already new standards such as Dolby Digital EX, DTS ES, TrueHD and DTS-HD Master Audio. Thinking ahead, go for a receiver that has a TrueHD and/or DTS-HD feature.
There are also Digital Signal Processing (DSP) effects that simulate the sound heard in many places such as stadiums, halls, arenas and operas. These effects are produced by the DSP chip, by applying equalization effects, echoes and balance changes.