Is there any way of using PatchMix to vary the volume of each output independantly?
yes of course! Each PatchMix strip does have a volume slider. To understand better the routing possibilities of PatchMix I suggest to read the article "Emu's Patchmix DSP Demystified":
http://www.soundonsound.com/sos/nov05/a ... tchmix.htm
Also there exists an audio forum with a very good section for EMU products:
http://www.productionforums.com/
Uwe