This should be easy but I'm stumped. I'm trying to run sound out of some passive speakers that are hooked up to a small amplifier, backside pictured below:



I tried this by running an optical cable "OPTI2" to the TV's AUDIO OUT plug. Then I changed the setting on the TV for AUDIO OUT. Well that's not working. If I run a USB cable to my laptop, the speakers work fine. So I'm pretty sure it's not a receiver or speaker issue. Any ideas? TV is a Samsung from 2012 or so.

Okay, so looks like an SMSL AD18. Just to double check, you are selecting the correct optical input on the AD18, right?

The other common issue is that that DAC only accepts PCM over optical. You need to dig around in the menu to find something like "Digital Output Audio Format" which will have options like Auto, Passthrough, Bitstream, and PCM. Switch that to PCM. If there's an option to select something like Stereo, Dolby, etc., pick Stereo as well.

There is a setting on your TV audio out for something like PCIM bitstream. Use that.