The Pro-1 is a mainly monophonic synthesiser, meaning that you can play one note at a time through it. However, if you wish to play chords (more than one note at a time), it is possible to poly chain multiple Pro-1s to achieve this.

First, you’ll need to have downloaded the SynthTool application. In this, you can change each Pro-1 to perform in Poly Chain mode. The LED on the Pro-1 will show amber when in normal mode, red when Poly Chain Mode is engaged but no notes are being triggered, and green when Poly Chain Mode is engaged and a note is being triggered.

Once Poly Chain mode is engaged on each Pro-1 you wish to use in this system, you need to connect a MIDI controller’s MIDI OUT port to the MIDI IN on your first Pro-1, then connect the MIDI THRU of the first Pro-1 to the second, and then repeat this step until all of your Pro-1s are in the chain. The main output of each Pro-1 will then need to be connected to the inputs of a mixer or audio interface to get all of the Pro-1’s output signals playing on the same system/ speakers. 

Once you’ve done all of this, you should be able to play chords through the poly chain system, with up to 16 voices (one for each Pro-1 in the chain).