Thx martadinata and Freemanix This helped! But I cannot get the output to work in Rhythmbox. What is interesting sound plays in Firefox. Moreover if I run Youtube in Firefox and start playback in Rhythmbox while Youtube plays I have output from both simultaneously, but as soon as I stop Youtube playback there is no sound from Rhythmbox again. Do you have any suggestions how to get it to work in every application? Thx!