As a closing remark I say that it is a total waste of bandwidth to use 24 bit audio on a DVD. Two reasons:
1) I would bet anything that there is no video or film (even $$$$$$$ film) where the total audio chain is 24 bit resolution. Mics are not, ambience is not, recorders are not, mic-preamps are not... It would have to better than a gloriously recorded classical CD to make it worth your while.
2) Even if the point 1) does not hold, I further bet that nobody has (ok, maybe 5 systems in the world) reproduction systems and rooms where they could fully utilize more than 16 bit resolutions. 16 bits gives over 96 dB dynamic range, for Pete's sake. With even really low room noise levels around 30 dB SPL that would mean over 120 dB SPL peaks!
Get real and use the bandwidth where it really counts: Video quality (less compression there).