We have an Epson projector with it's own speaker and DVD player. There is a Digital Coax Audio out port on the back. We want to use this for an external speaker. How do I go from the Digital Coax RCA type plug on the output to a standard speaker with a 5 way termination. It needs to be about 30 feet away from the unit.
The D RCA connects to an amplifier with a compatible D RCA input.
The speakers are driven by that amplifier.
The projectors output is digital, it must be converted to analog, before being amplified.
The amplifier with D RCA input contains the D to A convertor. Once converted, it is amplified, and can then power speakers.
I have no idea what "5 way termination" is, you have to give more details.
You can buy speaker system that has a coax digital audio input and a long enough extension cable. These are mostly for PC use. Otherwise you will need a surround sound receiver with a digital audio input. Since you don't really need surround sound or video switching you can get a older used one which should be cheap.