I've got the master channel but no speaker channel. Menotu, you don't have the speaker channel either! (that I can see in your screeny) I must say though that I'm not having any sound problems either. Kmix keeps getting curiouser and curiouser.
I installed 2010 KDE-minime. Had a weird problem with skype using a headset with the 3.5mm plug-in jacks. Did a gazillion skype test calls...I sounded like Darth Vader on 'luudes!
I finally replaced that headset with a USB headset and BAM...solved that problem!