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?