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.