Ya, that is why I have not pulled the trigger on the M2 yet. Hopefully the M20 still has good SQ, and they didn't pare it down too much.
It seems like a pretty radical change of electronics. I would be surprised if it sounded as good as the M2. Why keep both in production with a fairly hefty price difference otherwise?
I don't understand why they didn't give a variable gain to the M2 to accommodate different headphones. There again I know next to nothing about electronics!