I am using Kubuntu 10.10 and having a sound issue. I fully installed PulseAudio so that I could properly enable the 5.1 sound on my system. At some volume levels it sounds great, while at others it has a terrible metallic-sounding distortion. I have worked with the various audio tools I have installed and narrowed down the problem.

Here is what I have installed to configure sound settings: kmix, pavucontrol, alsamixer.

I have found that when I adjust the master volume level through kmix (either with the GUI slider or the volume control keys on my keyboard), the levels in alsamixer all change, too, not just the Master level. When PCM maxes out at 100, I get the distortion, but if it is at 99 or lower, everything sounds perfect. The weird thing is that as I adjust the master volume level, the PCM level bounces between 98 and 100. Like this:

[CENTER]Master PCM

23.....100
35.....98
42.....100
52.....98
58.....98
61.....100
68.....98
74.....98
78+....100[/CENTER]

Is there any way to lock the PCM level or cap it at 99? If I can keep the PCM from hitting 100, I can get rid of the distortion. I would greatly appreciate anyone's help.