I have a SoMA dock connected to a MacPro tower.
When I listen to headphones from this tower, I use an external DAC which improves everything. I can easily connect the DAC to the SoMA, but will there be a benefit in the audio or would I be wasting my time?
There may or may not be a benefit. The internal ADC in the SoMa is very high quality so adding an external DAC may help. I would be interested to hear about your results.