Yeah, some degree of isolation is probably a good idea. The issue wouldn't be an accident due to plugging into an output, but issues with bad grounding or a sho

Yeah, some degree of isolation is probably a good idea. The issue wouldn't be an accident due to plugging into an output, but issues with bad grounding or a short to mains. It's unlikely, as it would be a failure condition for the modular synth too, but better safe than sorry. I'd personally like 2-5k kV of galvanic isolation between me (and my $$$ prosthesis!) and the wall. Plugging into an output would merely make some op-amps unhappy. Maybe a little magic smoke, but nothing lethal... (Not a real EE and I'm definitely not confident enough to design interfaces between fleshy bits and mains-powered hardware.)