First experience with Ubuntu Precise

Hello, does someone tried to install Trinity on Ubuntu Precise? Today I upgraded my system from Oneiric to Precise due to new hardware that did not work properly on Oneiric. Everything works fine in Precise, except the sound. While I still have sound in gdm or in unity DE I don't hear anything in Trinity. Since the sound works already in gdm I think it should also work in Trinity if Trinity would not touch it at startup. Unfortunately Trinity does. Shortly after the start the sound gets somehow deactivated or invisible muted (in alsamixer everything looks fine, volume is up not muted). However, I don't hear anything and I don't get any error messages). What can I do? Regards, Stefan