[LAU] MIDI Routing/Mixing (Korg X50)

Hello everyone. (Are there any other Korg X50 users on the list?) I have an X50, and an Evolution MK-461C MIDI controller board. What I'm trying to do is use the knobs on the MK (and the X50, actually) to control the parameters on the X50, but I've got a major problem. It seems that the only way of getting either of the two keyboards (that is, the actual white and black keys) to control more than one sound is to assign all the sounds to the same channel. The problem with this is: Say I assign a synth pad and a piano sound to channel 1. Then I try to change the volume of the synth pad (using MIDI control 7), using the knobs on either the X50, or the MK (it doesn't matter which). What I find is that the piano, being on the same channel, also has its volume adjusted. Sure, I can use the MIDI filter feature on the X50 to say that the piano ignores volume changes, but then I can't fade out the piano if I want to. Anyone got any suggestions on how to overcome this? Currently the only way I can think of is to send all MIDI events via my laptop and get it to duplicate the note on/off events and send them to all the relevant channels. Is this my only option? Surely the X50 has a better way than this? Also, how well would MIDI cope with this? I have heard people mention that MIDI doesn't work so well if you send lots of data down it (like 8 duplicates of the each note on/off message?). If this is my only option, does anyone know of any better MIDI router/mixer software? Currently the only one I know of is soundfontcombi, but it's not very flexible, and doesn't work so well with JACK's auto patchbay connections. Thanks in advance. Simon