
KMix is prepared for multiple sound cards. If called via the KDE Panel, the default mixer is used. For the Open Sound System, this is /dev/mixer. For other operating systems or sound drivers, this may vary.
If you want KMix to use a specific soundcard (primary, secondary, ...), you must tell this KMix on startup. You can start the mixer with a device number, using the -devnum n parameter. -devnum 0 means the default device, 1 your primary mixer, 2 your secondary mixer and so on. If you use this regulary, you should create a new program kdelnk (using kfm or the menu editor). This should just call kmix with the appropriate device number as parameter, for example "kmix -devnum 2".