It seems to work with a particular jack, I can only say that I have tried with headphones Samsung S3 mini and worked perfectly. If you have chance test S3 mini headphones (I guess compatible with all samsung).
Typical response dilator ... Technical support Vowney asked not responding!
It is probably a hardware defect, but do not want the state to avoid returns.
If it was a software problem would have already solved, or at least they would have responded by stating that they would.
Ps the compass does not work even with the latest rom V5T!
I wanted to say that I am very satisfied with the V5 but I'm not absolutely Vowney that ignores the problem compass: does nothing and says nothing.
In this way Vowney will not go far ... In fact, it seems to me that the initial interest on this phone, lately has collapsed.