Love my MC-600 but the 2 mic inputs are way over sensitive. The volume controls are at a level of at about .5 (scale of 1 thru 10)
I dropped a -50 db attenuator in line but that causes too much hiss especially if you are switching the mic on and off with its own switch.
I tried a -20db one too and it's just more noisy than the afore mentioned.

Anyone have any other ideas? maybe there's an internal switch of pot that can be adjusted?