Are you referring to the Yggdrasil or Gungnir? I think you are referring to the Yggdrasil, as I do not read the "preserving" text elsewhere.
See the first question of the Gungnir FAQ (copied below):
Wait a whole entire second there, buddy! Are you saying that this has the same insane digital filter and multibit architecture as the Yggdrasil?
In the case of Gungnir Multibit, yes.
So with the Gungnir Multibit, you're essentially missing 25% of the content in all those 24-bit files you've been playing. Granted, this is material that lies at ~108 dB below full scale, so it's doubtful that you'd hear any artifacts. However, audiophiles can be a picky bunch.