I'm not thinking of having any connector. Just permanent extensions.
I think this would be fraught with problems in itself - unless you found a way of relieving the strain on your solder connections.
I mean for god's sake i have had many recorders and i dont kow what the M10 does or if it sheats but at low setting (or even high) quite performances are DEAD quite in terms of background hiss and no the ambient noise would have masked it if it produced hiss. No software hiss removal would apporximate it the results and you can call them cheap mics or whatever.
I know the M10's mics have received praise for their low noise but I still can't believe that (given the total price of the recorder) they can be really *that* great. Which is to say, that for minimal outlay I imagine you could get equivilent external mics - which means you wouldn't have to start modifying your recorder and would still have the option of
not running "external" mics.
My recommendation would be for a pair of DPA 4060s bought second hand on Ebay and soldered to a single 3.5mm jack plus a Sounds Pros 9v battery box. That way, you've got a fabulous pair of mics, the option of running your unmolested M10 on just the internals and the only extra gear you need to carry is the size of a 9v battery. Actually, my recommendation would be for those mics plus a Church 9100 pre amp but you seem to be looking for the absolute minimum of extra gear.
And have you tried asking around the Team Classical Music thread for mic recommendations?
I can understand your frustrations but I think you're looking for a rather extreme solution -and one which is fraught with compromises and pitfalls- to a problem many people have already found a very satisfactory solution to.
Maybe you'd get some more responses if you lost a bit of the attitude?