HDMI Ports
The number of HDMI ports in an A/V receiver determine the number of high-definition components that can connect to it. Devices that as of 2010 use HDMI include Blu-ray players, current-generation video game systems, HDTV receivers and computers. Future technologies may also use HDMI, so look for a receiver with more HDMI ports than you currently need.
Supported Audio Formats
Most receivers with HDMI support lossless audio formats such as Dolby TrueHD and DTS-HS Master Audio. This feature is important if you plan to watch Blu-ray movies, as they support these high-definition audio formats. Another important factor to consider is whether the receiver supports 5.1 or 7.1 channels, which determines the total number of speakers the receiver can send power to.
Wattage
Wattage is a measure of the total amount of power the receiver sends to the speakers, and it is usually measured per channel. Higher wattage means that the receiver can power larger, more demanding speakers and produce an overall louder sound. Receivers with higher wattage ratings also tend to produce a cleaner, crisper sound.
Read more: http://www.ehow.com/facts_6906819_compare-hdmi-home-theater-receivers.html#ixzz2jlBejo4C
