mixing matrix depending on number of input channels

[Rehn]

i was thinking about some function which would recognize number of input channels in audio (mono,stereo,4.0,5.1 etc) and depending on it would assign some preset matrix automatically. I use it very often, but now must do it manually (which is not practical). I discoveried this kind of function in Media Player Classic but there i cannot set a nominal value of  each channel volume (gain).
What do you think about it?