Update on my suggestions. Soundaware's replies in purple:
1. Neater case (using my example of how FiiO went from the X5 to X5II)
As the heat dissipation when playing, we ended the plan to make the case. We are making the protection paster.
I think that the next time you do a run of cases, see if you can't get the manufacturer to make the screen sit flush. IE: Now the player looks like this from the side:
______---_---_---_________/^^^^^^^^^^^^^^^^\_
It should look like this:
______---_---_---_________________________
I understand that other changes would require a major re-design. That's not urgent.
2. Power management fixes (as above).
3. More efficient UI showing 7 lines of browsing text, more info (eg: volume) at the very top.
4. 0.1 Ohm output impedance.
We are preparing to develop, try to decrease to be lowest OI as your suggestion.
This is an important one and should be the first priority in hardware changes.
5. Optical digital output (maybe using a combo socket with the coax output).
6. Coax digital output pinout fixed to the common standard.
7. (New idea) "IEM mode" with a lower power output and longer battery life when only IEMs are used. I'm not sure that the FPGA doesn't use most of the power in the design though, other than the screen.
8. M3U playlist support. The player should recognise song file paths in an M3U file, delimited by a forward-slash ("/"), relative to the location of the file.
About M3U, it need player to connect with the internet. I am not sure whether it's right?
No internet needed. M3U files are for playlists. They are just a list of where files are on the player or computer. They should support relative paths. When the player does a music scan, it should read any M3U files it finds and load them as playlists.
Eg: Absolute path (from my M3U file for another player)
/mnt/SD1/Music/Harry Manx/Mantras For Madmen/02 San Diego - Tijuana.m4a
Relative path (if the M3U file above is in /Playlists)
../Music/Harry Manx/Mantras For Madmen/02 San Diego - Tijuana.m4a
Your software engineer will understand this I'm sure.
I know playlists aren't important in China, but they are elsewhere.
9. CUE file support. Gapless support.
10. USB DAC support.