Both ARGON 8 and COBALT 8 synths have the ability to pass Midi messages from a Midi device through themselves and onto another Midi device.
There are 2 ways in which you can do this.
USB Thru
This takes DIN In -> USB or USB In -> DIN Out.
So device 1 can be Midi channel 1 and the ARGON or COBALT can be Midi channel 2 and the Modal hardware will pass the Device 1 data though to the other receiving device.
DIN Thru
This takes DIN in -> DIN out
In the same way, device 1 can be Midi channel 1 and the ARGON or COBALT can be Midi channel 2 and the Modal hardware will pass the Device 1 data though to the other receiving device.
You can locate these options in the Settings-Midi page on the hardware or in the Settings page in the app.
