Can anyone simplify (in novice terms) how I can stream movies from my "2009 era MacIntosh" computer - quality Audio and Video output to two separate sources? I want to stream the Audio output to my Onkyo TX-SR608 receiver and get 5.1 output to my home theater speakers and for the second source; I have an Epson 8100 projector of which I would like to use an HDMI cable connection for 1080 resolution. Seems simple enough, but in order for me to designate HDMI to my projector; it seems that I will then only be able to get stereo sound to my home theater speakers. Any of you geniuses out there have a solution for this? I've considered Apple TV but don't know if it will work either in this format. Any help will be greatly appreciated!
Simply in your HDMI connection into your mac, go to displays in system preferences and configure from their, to have audio streamed to your amp go to sound in system preferences and navigate to the output tab. Then select your amplifier, be it plugged in via headphone jack, USB or airplay streaming.
The signal path needs to be device to receiver over HDMI, receiver to speakers as per normal (or power amp), receiver to projector as per normal (presumably HDMI). So essentially get your Mac outputting to the receiver and you're golden, assuming that the Onkyo is already setup correctly.
What you could do, if you want to use an Apple TV, is you can simply plug the projector into the Apple TV's (provided it has HDMI) HDMI Out and the Onkyo into the Sound Out. Then you can use AirPlay to stream to it.
Just to re-iterate, no additional hardware should be required. This scenario is precisely why people invest in receivers (such as the Onkyo that you have) over and above an amplifier - its purpose is to intercept AV signals from various input devices and provide the ability to split out audio in high quality whilst sending the video to one or more outputs. Conceptually this is the solution that I've used extensively at home.
I would advise to persevere with the hardware that you already have.