I used to get the same thing when I reduce the buffer size to reduce the latency when working with audio software. Although this was on an old PC and part of the reason why I upgraded to a faster spec.
I'm not familiar with this particular DAC but I understand how they work and what can happen if your computer cannot work quickly enough to fill the audio buffers with digital audio infomation, to be processed by the DAC chips. And this usually happens when you ask the DAC to work at high sample rates or reduce latency by reducing the buffer sizes.
Check your settings and see if you make adjustments. Because you have to compromise between audio sample rates/buffer sizes and latency.
In fact i've just read the specs of this nice piece of equipment.
And i'd say drop the sampling frequency down to 44.1K and play audio through it while increasing the sampling frequency until you get audio drop outs.
When you get the drop outs thats your limit.