Summary of situation:
We have two systems, one upstairs and one downstairs. For the moment, they are called "Hackatorium" and "Turing" respectively (holdovers from the old space). They are very similar. The main component is a switcher that takes multiple HDMI inputs and has a stereo output and an HDMI output. At the bottom of the switcher there's a series of lights from 1-4. 2 is for Chromecast, 3 is for Apple TV. The light that's current on indicates which input is being sent through.
- Make sure speaker (on top of laser cutter) is turned on
- Make sure sound mixer is turned on
- Make sure speaker and sound mixer are connected
- Make sure HDMI mixer is set to whatever you want (3 for Apple TV)