Fwiw, I have similar experiences as you with the DPA 4063 going into the M10
mic-in PiP.
I suspect the mic-in is too hot for these mics on the M10 and the internal preamp isn't optimal when levels are at 1-1.5 (manual, low sens)
Using a battery box allows me to go line-in (levels in between 4 to 7.5 depending on show). I don't even believe going mic-in with external power is an option for me unless I'm recording a quiet acoustic show (haven't tried one, yet).