If you want play sound of your own devices via your Epson projector, you can connect the projector to the video source using an RCA audio cable. This article takes Epson Home Cinema 1080 as example.
Make sure the audio cable is labeled “No Resistance.”
Connect the audio cable to your video source’s audio-out ports.
Connect the other end of the cable to the projector’s L and R audio ports.
It is worthy to note that if you connected your video source to the projector using an HDMI cable, the audio signal is transferred with the video signal; you do not need an additional cable for sound.