You must be special if it works for you. It makes no difference whether I use a TRS orTRRS plug headphone, only the left channel works. I have a feeling SEEED may have used a mono jack but without a schematic and a jack part number it’s impossible to tell. Of course, SEEED will not come forward with this information or admit they made a mistake. It’s not worth my time to bother with this as SEED won’t respond. I’ll just use the HDMI audio, a USB audio card or a HDMI audio extractor box for sound.