After-market ANR - I know a chap who fits them as a sideline. Not had mine done, but those I know who have speak highly.
He replaces the pressure units in the earpieces with ANR modules. The microphone stays unchanged.
He has an "auto-off when the mic is unplugged" option, which also sorts out mic incompatibility (why is it that some DC headsets won't work with other versions of DC?)
If you want his details, send me an off-list message and I'll pass them to you.