I've just installed a fresh Ubuntu 15.04 and the first thing I tested was the sound. At first it seemed it works (the speakers are playing) but the subwoofer isnt working. As default the sound played through Line out, then I changed it to Analog Output/Amplifier and selected 5.1 output, but then I got no sound at all, also when I touch the subwoofer volume bar I get some weird noise like wind is blowing. But the sound is ok on windows 7.