My husband bought a new projector and wants to figure out how to connect the projector with our home theater, cable, and xbox. But the problem we are facing is we the home theater only has one hdmi output. Anyone know how to go about hooking all of the electronics so they all run through the projector and we can hear the sound?
It's generally done the other way. Connect all the electronics to the receiver and feed a single HDMI from the AVR to the projector. If you choose to make separate video connections direct to the projector, then you need to run audio, likely optical or coax, from each device to the home theater system.
Home theater receivers usually have several HDMI inputs so that all of the playback devices can be connected to the AVR, which processes the audio and sends video to the display over a single HDMI output. If your system lacks the needed HDMI inputs, then you would run HDMI from each device to the projector for video and either optical or digital coax from each device to the AVR for audio. If your receiver doesn't have digital audio inputs, then you may not be able to make much of anything work.
They make HDMI switches that allow many devices into one switch box with one HDMI out. The box switches automatically to the incoming feed, or I imagine they have selectable ones as well. Thus if you only have one HDMI input on the receiver a device like I mentioned would do the trick. I posted a link to one as an example.
Posted too soon... There should be an HDMI out on the receiver, that one out would send whatever is being accessed on the receiver to the video source such as a TV or in your case the projector. If that does not have HDMI inputs then you would have to use the splitter i mentioned to run video to the projector but separate audio cables from each device to the receiver.