I notice that the volume control is set by the modulation wheel controller in GPO. There is a separate dial (volume knob) calibrated in db but that seems to depend on the Mod wheel having some non-zero value. This means (as far as I can see) that for each GPO instrument there needs to be some value sent from MNC to the GPO to set the Mod Wheel.

This is the first chance I have had to use MNC (or any music software) for a few weeks but I recall finding a controller pulldown that included the mod wheel. Problem is this has to be set and resent at each playing of GPO - which, seems to reset the Mod wheel to zero! Is there perhaps a way for MNC to send some value (64 perhaps) to the Mod wheel at each "play" for each instrument that is to play? Otherwise it is almost impossible to drive GPO in terms of getting the volume levels right.

I think (again from memory) the piano is an exception in GPO and it may be controlled directly using MNC volume curve. (I may well be wrong there).

I hope the above makes some kind of sense, (been a very long day)!
-John