Hi Sparky589

Expression(Volume) control is normally cc11, (Don’t confuse with sound volume cc7) and if you make sure the Korg outputs this command over Midi, then you will only need the expression pedal connected to your Korg, as it will control expression (Volume) on both the Korg and SD2 simultaneously.

Check also to see if the Korg has any Midi sound banks (I believe the larger models do) as you can set these to select any Midi voice and setting on the SD2, (Don’t forget to save them as a user voice) and then use them as if they were a normal Korg user voice. (Effectively the SD2 becomes part of the Korg)

Hope this helps

Bill