The RCA cable that I purchased also has left and right audio out, so I’ll be making use of these for the audio. The original Gameboy DMG has a single speaker, allowing only for mono audio. As the output from the Pi has two channels (stereo), I will attempt to use two original Gameboy speakers.
The volume of the outputs is fine for headphones, but doesn’t pack enough punch to run the speakers, so I followed suit of many other Gameboy Pi makers and obtained a cheap amplifier:
I took both the left and right audio channel cables (the only two cables that are left, as we’ve already used the video cable), 5v and ground from the Pi GPIO pins and connected them as follows (image stolen from the eBay listing.
As the diagram shows, you then run two speakers off the + and – outputs of the amplifier. Here’s a picture of my amp wired up and ready to go.
Here’s a shot of the amp and speakers working.
Here’s a video demonstration.