I have already ran mics > MME standalone and did not have this problem. Perhaps a little distortion on the overs, but definitely no clicks or pops. I was using the Hosa cables as well (same ones I use now). I have a pair of Blue cables I can try.
Gotcha, I missed that somewhow.
If I ran the Shure attens in front of the V3, I would be pushing the gain to the max. Right now I am only pushing about 40 dB of gain with the mic pads or V3 pad. Don't see why another atten source would matter.
The amount of gain applied after the input stage isn't the issue with brickwalling. It's the signal pre-input stage. That's why the attenuators are worth testing, IMO. And I'd still test the other cables with the V3, even though you've tested the current cables in the MMe with good results.
Your best bet at this stage is probably to call the folks at Grace and talk to them at length and in detail about your experiences to date. I don't know the details on the V3, but when I ran a modSBM-1 I encountered similar problems because the op-amps started to croak. Maybe it's a similar problem? Whatever it is, Grace should be able to help - it may require sending the V3 back to them, but you have the MMe to use in the meantime, anyway. If anyone can help, they can.