Retired taper here who also used to own the M10 and the PMD661, but never used the internal mics. Fast forward 5 years and I want to buy one of the two again but mostly to use with the internal mics for --ahem -- recording loud music from my neighbor's house (to play for police when they show up after the music has already stopped, to buiild for a potential lawsuit in the future, etc.). In any case... they have eclectic tastes, ranging from hip hop to Indian dance music to new age sh*t. Would either of those recorders do a decent job of recording the music with the internal mics to get a decent sense of how loud it is? Would one be better than the other? I don't think distortion wouild be an issue because it's not close to painfully loud, just loud enough to bother us a lot. I would prefer to avoid using external mics, but I wonder if the higher cost of the PMD661 might mean the internal mics are better and it could be useful in case I want to actually get some "real" external mics via XLR inputs. If the M10 would be fine for this purpose that would be ideal I guess since it's a lot cheaper. I remember I loved both units in the past so no concerns about either in general, although it seems the Marantz is not even sold in the US anymore (or the MKII version either).
Any suggestions/input would be great, thanks!