Have an epson 9200 projector, samsung 5.1 surround sound and small comcast dvr secondary cablebox. And an hdmi switcher with 1 output and 4 inputs. I have a hdmi going from cablebox to projector and another hdmi going from projector to bluray player. When i play a bluray it uses the surround sound and projects great, when i switch over to cablebox then the audio switches over to the projectors weak speakers. I bought the hdmi switcher and then i plugged my hdmi from my projector to the output jack of the hdmi splitter and then an hdmi from the input side of the splitter going to my bluray player and an hdmi going from the 2nd input side of my splitter to the cablebox. Both bluray and cablebox work but same problem, as soon as i turn on cablebox, surround sound cuts off and audio goes thru projectors speakers. I messed with all the settings every which way and still nothing.
I would connect the 5.1/BD player and the cable box to the projector with HDMI.
Connect the digital audio output of the cable box to the 5.1 for sound when using the cable box.
Turn the volume all the way down on the projector.