Also noticed that my Win7 laptop doesn't recognize uSD card when I connect M1s, so had to copy files externally.
Been playing with M1S for about an hour, and so far I'm VERY impressed with Sound Quality, in particularly the Balanced output. A rather noticeable difference between SE and BAL outputs with improved transparency and layering, wider soundstage, better dynamics. Overall the sound is rather neutral, dynamic, with a nice transparency and retrieval of details. The sound quality is up there with some of the top mid-fi DAPs that cost at least 2x more. Of course, will be putting it through 100hrs of burn in, this is out of the box impression after 1+ hr of listening and 1hr of burn in prior to that.
My only gripe so far with d-pad "wheel" control which is a bit sensitive depending on how/where I press'n'hold to fast forward, and often skips to the next song. Seems to work better when I press L/R sides closer to the edge to fast forward/rewind.
Also, for those reviewers who got Lee's email with the latest FW, the upgrade is a bit tricky; took me a little while to figure it out. Copy the file to uSD card, but don't insert the card into M1S. Go to Settings -> System Update and after clicking ok and getting message "wait TF insert", then insert uSD with "update" file in a root directory. And after update is done, re-insert the card.