migrating from original SamplerBox hardware

• The USB DAC should have been auto detected. If you're OK, I'll send you a PM to try some debugging (no hurry, your solution is a perfect bypass).
  

I've just tried setting the audio device id back to -1 and it works fine, detects the USB DAC no problem.

So this was a red herring, it was just the MIDI serial that was my original problem.