Plasma voice looks way cooler than it sounds and it's a one-trick pony. Nothing wrong with that, of course. But if you are just getting started, I would suggest something more versatile. There are countless voices out there that can achieve that sound. I recommend Noise Engineering stuff for what you are proposing.
)
When you mention using external FX, I am assuming pedals, yeah? Either way, add a ADDAC200PI module and you can have access to two different FX chains with proper audio signal attenuation both ways.
Something like this combo seems to fit your request:
(Cheers
-- AEROCATONE
YES!!..Noise Engineering...well ,I want all their modules ...its just with this small systems i want to add something...that maybe im not easily able to achieve in other hardware synths ( maybe software yes...Newfangled audio Generate). Id love a NE machine!!!