You can use the MIDI Universal Controller tool for exactly this. You only have to route once.
Steps:
- Install the MIDI Universal Controller Demo tool.
- Invokes the tool.
- Turn ON the tool (top left button).
- Go to the first drop down list and click “Macros + Modulation”.
- Go to Renoise/MIDI Map.
- Map the first 8 sliders of the tool to your USB MIDI controller. It is recommended to use infinite spin wheels on your USB MIDI controller.
- Ready!
You now have all 8 macros of all instruments linked. Each time select each instrument to control them.
However, MIDI Universal Controller is much more than that!
Enjoy it!