Also has anyone by chance compared the 1350 M1 to the 1350 M2?
I'm quite fond of the M1 and feel it never got its due 'round these parts. A very unusual little IEM. I'd like to try the M2 sometime, which seems even less talked about than its little sibling. It's unfortunate the 1350 series, like the 1601 series, is out of production now.
I know this is digging back through the thread a little bit, but I thought I might share my 2 cents on these two. I own the M2, and I heard the M1 for a brief time. Comparing these 2 are actually quite difficult unless you own both, mainly because the sound changes as the time passes. I remember the day I first got the M2, I thought it was faulty, and then put it away for 2 months or so.
A sizable collection of my music have female vocals (for better or for worse) and when listening to them with the M2 I thought my eardrums were being stabbed, repeatedly. Compared to something, like the Adagio III, I would consider these would be considered biblically anaemic. Very, very little bass presence/impact, whilst in comparison the upper mid -> low mid treble is very forward. It's also quite quick, adding to the lack of warmth. The M1, if anything was more pleasant. Still not much bass impact, but also less offensive for the rest of the sound. I also found that the M1 to not be as detailed than the M2. Now whether that be lack of running time, or even the construction material (I think FAD put something into the M2 to make it less likely to reverberate, and also making it matte at the same time), I can't be sure.
Now more than a year on, and having put more than 150 hours on the M2, the unique sound signature has grown on me a fair bit, to the point where I use it as one of my main earphones (only with the slitted eartips tho). The aforementioned upper mid, low mid treble hotness has calmed down to tolerable levels, and classical music sounds especially good owing to its quick speed. What hasn't changed is how awful it sounds when you use any non-slitted eartips. Imagine being in a bathroom, and listening to music really loudly...that's pretty much what it sounds like. Add to that, those non-slitted tips don't isolate either.
I can actually see why it's not been a popular earphone, with M2 being even less so. For one, it was expensive, but more importantly, that sound signature, you either love it, or you get a massive headache. The M1 might be more tolerable, but really, they both go down the same path, one's just a little bit further along...