How Kodi to send only PCM audio?

Hello guys and forgive me in advance for the noob question.

I have a Panasonic ST60 that is connected with HDMI to my RPi 2 with Openelec/Kodi running.
I want to use the optical out of my TV in order to send it to my RCA receiver. Of course the convertion will be a done by a FiiO D3 DAC.

The thing is that this DAC supports only PCM input, while the TV is capable of PCM, DTS and DD output.
So:
What is best way through the settings of Kodi to send only PCM to the TV? I have disabled passthrough, but is this enough?

Thanks in advance guys.