OK so I'm new to the RME world - have been using a much less capable device that only had analog connections, and recently upgraded to an HDSP Multiface 1.

I run Windows 10 x64 and the Reaper DAW for audio engineering work.

I have my Multiface setup for 88.2 and have reduced the WDM devices to 1.   My intent is to replicate how I used my old audio interface with Windows audio going to one pair of playback channels, and Reaper DAW audio going to a second pair.   Both pairs route to Hardware Outputs AN 1/2 where my nearfields are connected and AN 3/4 where my subwoofer is connected.

I can't say that I hear any discernable difference whether I send audio to AN, SPDIF, or ADAT channels on the Software Playback line, but I'm curious....

a).  Is there any latency advantage or disadvantage sending Windows and Reaper DAW audio to playback AN vs playback SPDIF vs playback ADAT ?

b).  Does RME just consider 1 'better' for Windows and Reaper DAW playback back on the internal architecture of the HDSP or Multiface ?

c).  it would seem logical to me that going to SPIF and ADAT playback channels first would avoid a D/A, so that the only D/A being done is when the signal goes to the hardware outputs AN 1/2 and AN 3/4.  Am I wrong here ?

Even though it's not current generation, this device already kills with stupid low latency because of the PCI HDSP card, but I just want to be sure I'm using it in the best way possible.

Thanks!
Brian