Birthday DAC

Hi all,

I have been asked by a family member to help choose a new DAC as a birthday gift. ( wish my wife was as generous ).  My sister in law is looking for an R2R Dac; preferably tube based.  The only kicker is she wants a smaller size.  Her price range 3-5 thousand dollars. I haven't been down this rabbit hole for a while and wonder if there are any suggestions I could share with her.

Thanks !