I had not realized, but there is no output coming from my front left or right 5.1 speakers. I swapped the connections and the speakers work. I booted into 8.1 and all the speakers work normally. I can't think of any settings which might cause this to happen. So it looks like 10061 has a problem in this area. I do not know if this is what others have been having problems with the Realtek speaker systems. Maybe the next build, whatever it might be, will fix the problem. I noticed in the Build Conference, they were using Build 10072 for the demonstrations.