of course this motherboard is a really, really dumb idea. it's something interesting htat should be built a few prototypes of and nothing else. The cost is about $120 more than the non-tube motherboard, and that tube output is like the bare minimum/worst tube audio. and it still goes through the onboard DAC which is probably no better than most onboard audio's DAC.
only somebody serious in audio would want the tubes. they should get a sound card with straight digital output (not converted to analog and back to digital, resampled, etc) - $150 is a good amount to spend here so you get a good analog out if needed - and then build a tube DAC & tube amp