The MA-100 (and presumably the MA-200) does contain some OP-AMPS (operational amplifiers) that do the balanced-to-unbalanced conversion. The MA-100 is designed for mic-level inputs, not for line-level inputs.

It is powered by 5 volts from the XL1. Assuming a 600 ohm output inpedance, and rail-to-rail voltage swing, and trhe 6 dB voltage gain, you quickly see that the MA-100 will be hard into clipping with an input voltage of about -7 dBV.
The best input level is probably on the order of a -30 dBV mic level, as is sometimes available as an output of a mixer or wireles mic. Use the MIC ATT setting of the XL1 to go with this level for a better noise floor withthe XL1 preamps.