How do I hook up PS3 HDMI, cable box HDMI, and surround sound?

Typically you would purchase a Home Theater Receiver. This is a device which accepts multiple audio and video inputs from all your devices (cable box, game console, etc.) and then outputs the selected video to your TV and the corresponding audio to your speakers.

A surround sound system or 'Home Theater in a Box' (which is what you appear to have) also acts like a receiver (so you don't need to purchase one!).

However, unlike standalone receivers, surround sound systems are often very limited in terms of the number of HDMI/video inputs (and sometimes don't even have any video inputs!). In this case it's okay since you say you only have two devices to connect and your sound system has two video inputs, so you're fine.

Basically you just connect the HDMI outputs from the cable-box and PS3 to the surround sound system, and then connect the surround sound system HDMI out to the TV. The result is that sound input from your PS3/Cable-box will be sent directly to the surround sound speaker system while the video will be passed on to the TV from the surround sound system. You then select which device you want active (PS3 or cable-box) by selecting the corresponding input through the surround sound system.

The alternative way to set everything up (if you had multiple HDMI inputs on the TV) is to connect each device to your TV's HDMI inputs and the connect the TV's audio output to the surround sound system audio input. In this case you select the active device by changing the video input on your TV.

Hdmi To Cable Box

Connect HDMI from cable box and PS3 to sound system then another HDMI output from sound system to TV input for video.

i'd be interested in knowing this as well. I have 4 hdmi slots so i dont have any worries but im unsure myself if you can do what yo uare asking