I just got my Switch, to replace my Wii U. My TV (Samsung 65KS8000) is connected to my receiver (Sony HT-SS1200) via optical. My Sky Q box, Xbox One S, PS4 Pro are all connected to the TV by HDMI. But when I connected the Wii U this way, it wouldn't do 5.1 audio. However if I connected it to the receiver via HDMI, the 5.1 audio worked fine. Now, though, I can't 5.1 audio from the Switch no matter whether I connect it directly to the TV via HDMI, then TV > receiver via optical, or connect the Switch to the receiver via HDMI and the receiver to the TV via HDMI too (which is the setup that worked on Wii U). I went into Switch settings and set audio to "Surround", no change.