Software (sample based) volume control - not touching mixer

Hi,

I'm using xmms in multi sound home system, where I want to mix several xmms
outputs also with speech (wav files) and other sources.

For this I need to control xmms volume on sample basis - not touching
anything on mixer device - just shrink and expand sample values...
(not using PCM,Vol control - cause in this case I cannot set different
levels for different instances of xmms).

I know that Alsaplayer is doing this (and is for now the only one I know -
and this feature is highlighted as advantage in several reviews), but I'm
not sure about xmms.  I've written this to General discussion, but obviously
this feature isn't present.

Any chance to change that ?

Thanks,

Robert.