Yes I understand the drawbacks of unbalanced gear. but I don't want to run all my keyboards through DI's at home, that is the only reason for the question.
I was under the understanding that the pres on the X32 are robust enough to handle line level signal. The only question was about what happens when an unbalanced signal comes into it. The downside is that the signal has to go through an actual mic pre too I suppose, but if the pre is robust enough to handle the line level, then its not a big deal, other then having to make some special cables or perhaps I will wire up a snake of some kind for this.