+1 docknow
Looked it up, yes I would suggest this could be a great solution without needing to open up the USB plug and soldering in a plug and lead to accept 5VDC input.
In terms of absolute fidelity, it would be more work to dismantle the USB connector B to the DAC, and solder in a barrel plug with a lead. I only say that because materials and lesser connectors may or may not introduce more or less noise.
From this diagram above, you would need to introduce 5VDC to 1 and ground (which will be negative in the circuit) to 4.
If you do go this route, a linear power supply is truly the way to go, and you need both conductors soldered into the USB B plug, if there’s no potential difference there will be no power. If you purchased it directly from them, perhaps you could ask if they would solder in a barrel plug that would accept either a male of female from a LPSU. No, not a switching power supply in the photo below, just showing you a barrel plug.