Been trying things all day and this is driving me mad.

I have the Sonos arc hooked up to the LG via the HDMI Arc. I also have a 1TB Sky Q box.

The issue is around the Sky Q sound. In the audio visual settings, the sound for Digital audio optical HDMI sounds better on original vs Dolby Digital. Much fuller and I can’t quite work out why! Thought it would be the other way around and I’ve tried on a bunch of HD channels.

LG Tv settings are as follows;

DTV Audio Setting - Auto

HDMI 4 - Bitstream

Digital Sound Out - Pass Through

eARC - ON

Am I missing something or got something wrong? Any ideas?