I have just bought a set of MDR ds6500 headphones. I use them with my Bravia TV whilst my wife listens to the TV speakers. The two sounds are not in sync! I have other wireless headphones which do not have this problem. The effect is an echo which is very distracting. There is no difference using an optical feed from my SKY+ HD box and the line outs on the TV. Has anybody else experienced this or know of a cure?