Neither of those. I use a Signal Splitter- HDfury AVR Key, after that the signal goes into my Oled B7 TV and another goes into Sony MDR-HW700 which is a pretty good headspeaker for movies.
Perhaps its an issue with the AVR Key, but as described previously, if I switch audio streams a couple of times, I usually get to the one I want.
It could very well be your HW700. Have you tried a direct connection to the HW700? I see that it has a HDMI out.