The Schiit Modi 2 and Uber what what I understand use a Delta Sigma (single bit, Bitstream) type dac. The Modi Multibit as the name implies uses a Multibit dac.
If your playing only PCM (CD, Redbook, or PCM downloads) then the more expensive Multibit option will give the best sounding conversion of it.
From MoJo Music:
" When a PCM (CD, Redbook) file is played on a DSD, Delta Sigma or Bit Stream converter, the DAC chip has to convert the PCM to DSD in real time. This is one of the major reasons people claim DSD sounds better than PCM, when in fact, it is just that the chip in most modern single-bit DACs do a poor job of decoding PCM. "
Cheers George