DVDA supports no-recompress for 16 and 24 bit PCM stereo .wav files with sample rates of 48 or 96khz. If you bring those into DVDA, they should not be touched- the green check mark in the optimize window will tell you the recompress status (green checkmark= no-recompress).
This still means you currently can only create DVD-Video with DVD-Architect.
Have you managed to get a DVD-V to play on a stand alone DVD player, with 24/96 sound? Theoretically, it is possible, but it doesn't seem to work in practice.
Patrick