Hi John,
Thanks for letting us know. Sorry to hear this is still an unresolved issue.
I’am not really sure where we can go from here, as this issue appears to be limited to the RPi kernel itself (confirmed by Brian with NanoPi Neo working), and USB snd driver.
Unfortunately i’am short on time at the moment, and in all honesty, I dont believe I can find a fix for this in the kernel.
Not ideal, but a quick fix (minus delivery time) would be to purchase a NanoPi NEO for this DAC.