Since I use Ubuntu, a linux-based OS, I am unable to use the Universal Control GUI. I have tried many routing options in my DAW, Ardour, and in my audio routing program, JACK. I cannot figure out how to get the 2nd headphone jack to work. I know it is connected to output channels 3&4, but nothing I have tried delivers. Is there a kind, linux-oriented soul out there who can help? I also could not seem to find any other dedicated interface mixer that would help.