Allegedly, on or about 18 November 2016, fred roller sent:
I make gross assumptions that audio dvd means you just put audio formatted files on a DVD of course, so please take with a grain of salt.
DVD-audio (or DVD-A) is a different beast than DVD-video (the names should give you a clue about purpose), and vastly different than random kinds of audio data files that happen to be on a DVD (but could be on any medium).
DVD-audio was intended as an usurper to compact disc digital audio (large disc capacity, room for lots of audio, quality-wise, time-wise, and/or multi-channel). But it never really took off and DVD-audio is a rarity, and finding a player for it is even more unusual than finding the discs. I've never seen any in a shop, I think it'd all have to be special order.