Yep, as everyone is already saying, I'd definitely run the -10db pad on the 140s. Pretty much a necessity I found with the MV100, though I only had km184s at the time, so I had to go with -10db attenuator cables. The MV100 can take a pretty hot mic signal on the input side, but it can brickwall fairly easily on the output side. With a minimum of 20db gain and with loud PA recording, I found I was brickwalling on the output pretty often with the 184s. Solved the problem when using -10db attenuator cables, so I would definitely recommend engaging the pads on the 140s.
I decided to get rid of the attenuator cables and just mod my MV100. So I changed out the gain setting resistors in mine so that it had something like a choice of 12db-19db-27db of gain (forget which exactly at this point).
Marc -- I would definitely recommend changing the gain on yours. With the gain change and with changing out the AD SSM2017 preamp chips for the Burr-Brown replacements, that would be a really nice stealth preamp. Sorry, I'm not of much use with the specifics, I did my mod 4 years ago and I really don't remember. I'm sure with the schematics it should be easy enough. I never had them, but as I recall, it seemed like the 2017's in the MV100 didn't use three completely separate resistors for the 3 gain choices, but rather did something like resistor1 for gain setting 1, resistor1 in parallel with resistor2 for gain setting 2, and resistor1 in parallel with resistor2 in parallel with resistor3 for gain setting 3. It made it a bit of a pain to choose resistors for getting exactly the gain settings I wanted. It was easy enough though to remove the surface mount resistors and replace them on the existing circuit board pads with regular (thru hole) metal resistors.