Question Hdmi audio extractor voodoo?

Mar 13, 2021
Hi everyone. I have a fire tv cube connected via hdmi to a Sony bravia, and the TV optical audio going to a cheap dac which is feeding an amp+passive sterio speakers. I'd like to be able to play Spotify with the TV off. I was also getting some problems with audio lagging the picture. I decided to try an amazon basics hdmi audio extractor so the audio signal didn't have to go via the TV.

However, the optical feed out doesn't seem to give any sound. Headphones plugged into the audio extractor get sound, and the hdmi signal carries on to the TV as normal. If I unplug the optical cable from the extractor and plug it into the TV audio out, it works as normal, which reassures me I've not done something stupid like got the amp on the wrong input!

This seems very weird. The extractor seems to be extracting the signal to its headphone out so actual extraction must be working. I don't have a coax cable to try that output.

Has anyone got any suggestions? Thanks