It doesn’t really matter, since a very “quiet” room (or headphones) has about a 30dB noise floor, so you don’t really get much useful from the extra 8 bits, even assuming that the audio actually uses the full dynamic range available to the format. More typical rooms have a 50dB noise floor, making the extra 8 bits completely useless, since anything encoded by the lower 8 bits will be below the room noise floor.
To make the full dynamic range from 24 bits audible even with headphones would require peaks of 178dB, which will likely rupture your eardrums even with only a few seconds of exposure (it’s about the same noise level as a flash-bang grenade).