Don't know if it applies here but in these cases we have used a zone out off of the audio matrix (in our case it's 100% the Zektor proaudio 16). The headphones themselves are like their own "zone" straight from the matrix out to the transmitter. If there is any latency, the built-in delay adjustments (on the lip-sync model) will accommodate for that. Output level adjustments too, etc. +1 on the Sennheiser RF units. We've used Sony too.