Thread: Checking voltage range
I'm mostly in camp "by ear" too for signal levels too, as Jim says the worst that happens is that something clips off a bit of the signal. Definitely occasionally throw envelope signals into Mordax to get a look at what they're doing though!
IMHO though, other than tuning you really shouldn't chase all that much precision in signal levels! Let it be a little sloppy, it might do something cool!