* 2) Mono Handling:
* S:Mono: Copy into all D:channels
* D:Mono: Copy in all S:channels
*
* 3) Mix D:Left, D:Right:
* D:Left: If not connected, avg all S:Left
* D:Right: If not connected, avg all S:Right
*
* 4) Mix D:Center
* If not connected, avg all S:Center
* If still not connected, avg all S:Left, S:Right
D:Mono should be similar to D:Center avg all S:Left, S:Right
* 2) Mono Handling:
* S:Mono: Copy into all D:channels
* D:Mono: Copy in all S:channels
*
* 3) Mix D:Left, D:Right:
* D:Left: If not connected, avg all S:Left
* D:Right: If not connected, avg all S:Right
*
* 4) Mix D:Center
* If not connected, avg all S:Center
* If still not connected, avg all S:Left, S:Right
D:Mono should be similar to D:Center avg all S:Left, S:Right