Which USB isolator should I choose for a hi-fi or audiophile setup?

For hi-fi and audiophile use we usually recommend the 7055-C. It is optimised
for the audio frequency range, has low parasitic coupling between the two
sides, and works with USB 2.0 and USB 3.0 devices.

A higher isolation voltage, such as the 5 kV of the 7055-B, matters for
industrial and medical installations. For consumer audio it brings no
advantage. The noise reduction of the 7055-C is what improves the result.

If your DAC has its own power supply, the differences in external power
handling between the models do not matter for you. Choose by noise behaviour,
which again points to the 7055-C.