I got an SM57 for my MOX8 after reading reading the various threads that there should be enough signal for the MOX8 preamp. I can confirm that you will need a preamp (unless the preamp in your MOX8 is different to mine).

Yes, I have the input set to mic.

Yes, I used the +6dB settings.

Yes, I have the input settings setup correctly.

Yes, I hear sound (either directly from the keyboard or via cubase) and the signal is just too low to be useful (noise free). I went and got cheap preamp and the results are great.

Agreed that the MOX requires some sort of mic pre-amp in order for the vocoder function to work (at least with my setup, and I’ve tried several XLR mics).  I’m using a Shure PG58.  On the MOX, I have A/D INPUT GAIN turned to 100%, UTILITY > GENERAL > Mic/Line set to mic.  Hopefully Yamaha can address this gain issue with a future software update, as it’s not really feasible to “simply plug a microphone into the MOX and you’ve got instant vocoder” like the marketing seems to indicate.  I understand it probably does work fine for some mics, but with mine there is no choice but to carry around extra gear (mic preamp).