Insufficient input. What will the DAC be fed from?
In front of a headphone amp (i.e. as a pure line-level source) you basically don't need a fancy DAC. On a computer where you generally have digital volume control available so headroom (for intersample-overs) is not a concern, a Topping D10 Balanced would be more than sufficient. (Or if you have use for a phantom-powered mic input among other things, I might also be looking at an Audient iD4 MkII which is about the same price, though it doesn't do more than 24/96.)