For the experiences I've read about this module....
Could it be possible to Sumarize your experiences and configuration??
(I'm getting frustrated because of wrong SDs -I've already checked 4-)
Jumper : 3.3 or 5 v
SD: Brand, Size, Format...
AD4 files: Speed, Rate, etc...
I think this will be a really usefull way to help new users for this module to be sucessful on their attemps.
NOTE:
And... Why not have that information populated under its own topic. "Audio players", "WTV020-SD-16P"