Group with two Dacs and one dac is off

Setup:

2 Fiio interface.

2 USB Dac

Fio #1 is linked to Dac 1

Fio #2 is linked to Dac 2

Fiio devices always stay ON but I turn off Dac 2 because it is tube based.

In such configuration, if I have a group with Dac 1 and Dac 2 and Dac 2 is OFF, it says “Can not open audio device”

In case of a group, if it can’t open an audio device, it still should allow playing on the other devices.

The behavior is correct. If you power down a device in the group, the group is broken, so you should unlink the device you want to use.