Just a super quick look at the source, without understanding the inner workings, the panning law is on _AHI_SetVol (), on sound.c. Now the part that does the panning seems to only be changing the volume of the left or right channels (i.e. doesn't make the left channel appear a bit on the right like others). I must be totally wrong but doesn't this mean that the mixing routines don't have to be modified and implementing say a sinusoidal panning law would simply be a matter of calculating the volumes for the L and R channels accordingly ?