I have done this a couple of ways. The dead simple method is to set every track to the same MIDI channel. Now any MIDI CCs you send to it will work on all 8 tracks simultaneously. Of course, now that everything is receiving on the same channel, it’s no longer effective to use any kind of pad or key controller because it will trigger all the sounds at once. If you’re not playing/sequencing the Digitakt externally then this is not really of concern. I did this with my BeatStep Pro here: https://www.instagram.com/p/BgCMXAVDRoO/
Second way this is possible, with the addition of externally playing on all channels, is to use a computer. How you do it may differ but I was able to achieve it in MIDI-OX using the Data Mapping tool. I effectively duplicated the output of my MIDI controller across all 8 channels. The controller you’re using for the Control All effect will still trigger all 8 channels if you play a note, but you can now employ a second controller to use keys or pads to play each track individually. Other apps will also allow for MIDI transform/translation, for instance you can program it in Cubase. I think with MIDI-OX I can actually fine tune it to Here’s a demo of me doing this method with my iPad running TouchOSC and a XY screen I made: https://www.instagram.com/p/Bhum3I1Aq9f/
A new way I just discovered to do control all from an external controller is to use the RetroKits RK-002 MIDI cable. With the polymux firmware installed, the cable turns a Digitakt into an up to 8-voice digital synthesizer by playing notes in a “round robin” fashion across your various MIDI channels. An additional benefit of this is that it duplicates all of the CC messages coming through it across all of your polymuxed channels, giving you control all. Like the above methods, you’ll no longer be able to play the Digitakt as individual tracks from the controller you’re sending CCs from, but a second controller will work.
