Border Patrol DAC - USB or SPDIF better?


For those who own a BP DAC, does the USB or SPDIF input sound better? I asked BP and they've never compared them. Mine has both and I'm upgrading my server/renderer to an Aurender N100. Trying to decide if I go with one with just USB (H model) or another $600 for the SC model, which has both. 
23a18cd7 f9e4 4e3d 93e6 457ef97c160agreg7