No sound running Volumio Sparky 2.586 on Allo USBridge to the Musical Fidelity V90-DAC. Have run setup a few times. I good option here might be to allow the selection of a generic USB DAC in addition to the V90 to attempt fall-back. By the way, because your OS is overwriting the MAC address on each USBridge (with the same value on each device), only one USBridge is on the network when the failure occurs.