Copy icons to folder that is shown in screenshot 3.
(If you like, be "careful" to save the original kmix-systray icons before override them, but, don't worry, there is no danger if they gonna be replaced :-D)
Maybe little adjustments are edited soon (position of muted-icon could be higher and/or turning the icon 45 or 90 degrees).
Icons are taken from crystal-svg,
so the Credits go to its author..
how i did:
removed "green waves" and downscaled icons to 22x22 pixels using Gimp.
thanks and enjoy :)