I have 2 nanos and it is Not Overkill At All. In fact it opens up So many more possibilities – you can do FM from one VCO to the other, you can use the VCA for more than just having an envelope control the amplitude of the sound, you have 4 LFOs and 2 loopable envelopes – SO much can be done.
But you probably want to GROUND one to the other and it’s very simple. Run a jumper from one of the Ov pins in the Sensor Block modules (over to the right) on one nano into the same or similar pin on the other nano. That’s what worked for me. I had some noise before I did that – afterward, none.
You probably want to pick up some more 12 inch (30 cm) jumper cables so that you can reach as far as you can dream. [g]