If he wants R2R instead of Delta Sigma then Holo Springs or Denefrips Ares are worth looking at.+1 on that both very good sounding R2R.
PCM, Redbook, 16/44, 24/96, or DXD. is bit perfect when converted by R2R Multibit.
DS (Delta Sigma) can only give you a facsimile of it, and is also bit of a yawn to listen to. But can do DSD or SACD
Cheers George