I bought the whole PO-10 series this week and the TE sync cable pack but am having trouble making secure connection between the units with each other and my headphones. I cannot fit a standard TRS cable all the way into the audio jack! I have tried to see how far a toothpick would go and it fits to the same length as a TRS cable. When I try with one I get about 4/5ths the way into the jack and am meet with a large amount of resistance. I have tried to push past it but get scared of breaking the units. Has anyone else had these issues? And does anyone know if I'm just being stupid?