I do not use the set up you mentioned but i had a hum a couple years back with my DPA 4022> denecke PS2> blah blah
but anyway what it happened to be was a bad connection from my transformer RCA's male to female, the connection gave off a hum.
I know this is not your rig, but i guess what i am trying to say is that it might be in your connections not the mic. In addition, it was only the 2nd time running my particular set up and i got hum, so it had nothing to do with use or over use, just bad connectors