The line-level inputs on the 302 and 442 are attenuated by 40 dB from mic-level and go through the mic transformer. We chose this topology to maintain transformer isolation of line inputs. For our portable field mixers we chose to keep their size small and not have transformers large enough to handle line inputs. The alternative, electronically balancing line inputs along side transformer balanced mic ins, was not practical. The noise penalty is extremely small, since the noise figure of the unit overall is quite low.