You can play keygroups with an external midi controller and the functions associated with keyboard playing (velocity, sustain, aftertouch) will come through to the MPC.
You can also trigger the pads of drum groups from an external midi controller.
You cannot control anything in the MPC with a CC control at this time. There is no way to assign a CC from a nanokontrol, for example, to control the filter sweep on a pad, or the volume of a sample. I might be wrong, but I have emails in to akai and multiple posts on multiple forums about this an no one has answered me yet.
On the official Akai support forum they do come out and say that you cannot 'assign' a controller to a parameter, so I'm 99.9% sure we've got our answer. I'm holding out hope that there are things you can control (but can't custom 'assign') and I just haven't been able to figure out what they are yet.
I recommended to Akai that you should at least be able to control the qlinks with external midi CCs. No word back from them on that yet. I would say they have a 50/50 chance of implementing something like that eventually, but I wouldn't expect it soon and I wouldn't buy the MPC assuming that you'll be able to control it with external midi CC in any meaningful way at this time.
