Oh, I understand now! Sorry, I didn't read your other thread before reading this one and I was wondering ... "Um...whied this guy sand his mp3 player?"
Heh, sorry about that ^^;;
Here, take a look at this:
meizu m6, For MP3 Players items on eBay.com
A metal case, crystal case, or even silicone case might help you. But I recommend a clear crystal case for your situation. You mentioned earlier that you don't want to hide your m6's aesthetic beauty. A clear crystal case will protect the back of your device from sweaty fingertips without compromising too much of its beauty. There are many different kinds of crystal cases, but here is a picture to show you what one looks like:

Source:
MEIZU M6 CRYSTAL CASE BRAND NEW WITH NECK CORD - eBay (item 200127450543 end time Sep-01-08 09:53:01 PDT)
(I am not the owner/creator of this image)
It will help protect the surface from scratches and fingerprints as well!
Hope that helps~