I understand what you are saying, and I tend to agree.
However, an external USB to S/PDIF converter offers flexibility in choosing a DAC of your preference.
I have not heard Benchmark DAC-1, based on some reviews it sounds cold and analytical, for this reason I am reluctant to buy it.
So my dilemma is, will this additional and seemingly unnecessary conversion to S/PDIF in an external converter destroy all the benefits you may gain by selecting a DAC you prefer that does not have USB interface?
It would be an easy choice if I could hear and compare all the devices, but it is not possible.
For example, do I go with USB to S/PDIF converter driving my MF X-DAC, or LavryBlack DA-10 which I am considering as replacement for MF, or do I go Benchmark DAC-1 with no USB to S/PDIF converter in the chain, assuming Benchmark will outperform any other DAC fed from external USB to S/PDIF converter, simply because of this additional conversion step.
What a pain this hobby is.