Hi I refer to the my own question from the 29/09/2021: Jack shows 22 outputs but only 8 produce a sound output I have added the aplay -l and -L output in the appendix. I have found a workaround. If the Fireface 802 is operated in ClassCompliant mode and you have an iPad available, you can route the Fireface 802 with the iPad and Totalmix Fx App, which is the actual purpose of the ClassCompliant mode. The routing can then be saved in the setups and the multichannel mode can be set. Then I can just plug the USB cable back into my Linux PC and get sound output for all 12 channels. It's a bit of a hassle, but it works. Best regards, Sebastian