Do you need any gear (mixer/pre-amp/?) in between microphones and the LX20 analog inputs (-10db)? Would you expect to have clipping if you ran a mic direct in?
Yes you do need at least a mic preamp...either from a mixer or a dedicated mic pre. You wont get clipping if you plug a mic into the ADAT, infact the opposite will occur. The mic level signal is not strong enough to give you good levels on the ADAT. The mic preamp IS necessary.