I do not know if that is a real usecase. I mean why would anybody on earth choose flac over DTS-HD track? If he has nothing instrument to play DTS-HD than it was meaningless to choose an .mka with DTS-HD instead of a simple flac track. If he has the ability to play DTS-HD he shall not play it as a flac. Either way not much of a point to select within the .mka.