PS4 slim - why isn't there an option to force 2.1 stereo?

Is there no longer an option under sound settings to force the PS4 into 2.1 stereo?

I've my PS4 connected to a projector and speakers and the sound is being outputted at 5.1 constantly. when Blu-rays are played, you can see this 5.1 by hitting the options button and there's no way to change it to 2.1

As a result all voices are muffled.