Request for Many Software Enhancements of this Awesome Player! 
Great player for the mini DAC-DAP lovers! I have a few of them. I see it as THE niche player going forward for replacing the SanDisk Sansa line (long-time Clip fan here), especially if Rockbox is ever developed for it, BUT I offer some suggestions for future firmware modifications to enhance this already wonderful player and make it top notch:
Audiobook m4b recognition:
Complaint: m4b files simply renamed to m4a play just fine but it's tedious and unnecessary to rename a large collection and when not wanting to alter the files, even by extension, as the player is capable of playing them as .m4a.
While we're at it, but not being too demanding

, recognition of .mp4 files for audio playback would be nice too! Some audio players on the PC do this just fine. I'm sure the M0 Pro could too.
Possible fix: At the firmware simply add .m4a into the long lists of formats that the player is already able to recognize. As long as the player then sees the file, it will play it just fine as proven in the experiment of renaming it from .m4b to .m4a.
And while there, of course add a bookmarking ability for whichever title is played. Rockbox had this for the Clip. A separate Bookmarks section that held the last time position of numerous titles that were played.
Audiobook bookmarking:
Complaint: The only effective way I can resume audiobook playback after powering off the device is from the Now Playing section IF I did not play some other file afterwards.
Or to resume from the Frequent or Recent section but that ability is finicky. Sometimes a recent entry will be saved for the same track of an audiobook each time it was resumed, creating multiple entries for the same track, so if the user listens to the end, they may have the device play the same track again but from a different timestamp! Very frustrating. Or have the player go to some sort of music file instead of going to the next track of the audiobook if a multi-file audiobook (i.e. several mp3s instead of 1 m4a/m4b).
Preference: Model how Rockbox effectively stored the last played location as separate and well-organized bookmark files. It would basically store just one bookmark for the one audiobook title, whether a single m4a/m4b file or multiple mp3 files. It seemed to be folder-based for audibook folders containing multiple files.
I already searched the forum in regards to bookmarking and noticed several posts but I am placing it here as it is part of my master list of requests.
Update to add a bug that was discovered when using bluetooth headphones and resuming from the "Now Playing" screen:
Resume "Now Playing" location issue with a long file & BT headset: From a powered off state and a bluetooth earbud in its case, upon inserting the earbud and turning on the player, resume starts way too early (at the location before the last pause if one was present before) and not at the most recent pause location. For example, the player would resume at 00:59:04 instead of the more recent, previous pause of 02:30:07.
Cause (repeatable): After pausing, inserting the earbud into its case before powering off the player results in this issue. This of course results in a BT disconnection which changes the audiobook timeline to a zero time location, 00:00 of 00:00.
Workaround: Always pause the player and shut the player off before the earbud is put away/disconnected. When returning back to the player, the timeline may briefly show 00:00:00 until the bluetooth headset gets paired and then usually the audio should reposition to the proper time of the last pause and successfully resume from that point.
Here is another reason why a proper audiobook/long file bookmarking feature should be implemented.
Wake player using volume wheel or screen tap/hold:
Complaint: During use and after the player's screen goes off, the only way to wake the player is to press the button. Because accessing the player from a black screen while in use is a very common action I believe this would greatly shorten the lifespan of the button. Also a minor 2nd bother is the noise of the button in quiet environments. Say for example your partner is trying to sleep and you have to press the button dozens of times to randomly navigate among folders when not using playlists. A few occassional presses is fine though.
Prefence: Add into the firmware the ability and option to enable or disable waking the player with a volume wheel turn. And/or if possible, either touching the screen or a 3 second tap-hold of the screen to wake the device. Although there may be no power to the screen while it is off and the player is in use so it may not be able to register any touches. But the volume wheel is of course responsive in that state so I think that the volume method would work with a simply firmware edit.
There could even be a setting to adjust the amount of wheel turn before the screen activates. For example settings of a 1/8, 1/4 or 1/2 turn in order to prevent unnecessary waking with accidental turns when the device is in a pocket.
Volume adjustment when the screen is off & higher quality wheel in future versions (if any):
Complaint: The volume slider, nor the main screen appear during wheeled volume adjustment when the screen is asleep
Preference: It would be helpful if at least the volume slider appears when the user makes a volume adjustment when the screen is asleep, with an option to enable or disable that feature. This could tie well into the preference I mention above, to wake the device, showing the main screen, by using the volume wheel. Maybe even having an option to show just the volume slider or the main screen with the slider.
Wheel button quality:
Some other people have also reported issues with the wheel button.
https://www.head-fi.org/threads/sha...now-with-balanced-output.965329/post-18201040
I'm thinking that it may be a downside of this player over time. As much as I praise this device I am noticing that the wheel turning action feels sort of flimsy, weak and of lower quality. This current player is a new device that hasn't been used excessively.
Half of the time the volume adjustment is unresponsive. I have to slightly tilt the wheel inward as I turn in order for the contacts of this potentiometer to make better contact. Even before I started the tilt technique I noticed that there is just too much side-to-side play in the wheel. As if it feels like it's going to break off soon. But the push button action is very good. Strong and with a nice positive click.
As much as I really like this player I think that this wheel is the lower quality part of it and I'm suspecting will fail in regards to volume adjustment for a lot more people as they use the player more.
Considering the most likely fate of this wheel for possibly several users it would be nice to at least see someone at YouTube do a replacement with a different wheel button or even a similar one if an aftermarket one can not be added.
Maybe if Shanling releases another version of this player, for example the M0 Ultra, they will implement a better quality wheel button. The Sansa Clip and smartphones have up/down buttons which work of course, and I'd take those, but a wheel is nice too.
Update: I just discovered that all along during the complaint mentioned above the wheel could actually be pulled out of the player! Because that is obviously not a typical direction I of course never tried that. But right now while trying to diagnose the issue I pushed the wheel inward and then lightly outward. I noticed more movement until the wheel could be pulled fully outward! Looking at the inner shaft of the wheel it is difficult to determine if the shaft broke or the wheel itself is designed as a separate unit. I decided to put a small dab of superglue on the end of the shaft so that the wheel does not eventually fall out over time and get lost! I will say again that even though I greatly like this player overall it really needs a better quality volume wheel!
Complaint: The wheel does not seem to be as good of a quality as the rest of the player.
Preference: Utilize a higher quality wheel or up/down buttons in a future release (if any).
Waking device shows the now playing screen:
Complaint: The user does not always desire seeing the now playing screen when waking the device.
Preference: Wake to the last visited screen and not always to the now playing item. Reason: In case the user was navigating within Settings, Folders, etc and in the middle of their task, while briefly attending to another item outside of the player, the screen timed out, then they want to return to that last location to resume their desired task.
Scroll file & folder names horizontally/left-to-right:
Complaint: The scrolling is not automatic and is quite tedious to do so manually with the fast swipe left action for each item. It is also only 1 time so it has to be performed again if the user missed it.
Preference: Automatically repeat-scroll the top item in the list.
Recent list clearing: Clearing recent entries at My Music - Frequent and Recent.
Complaint: Clearing many items becomes tedious and there is a bug where not all items get removed despite the user removing them multiple times and are not being actively played.
Preference: An option in Settings to not retain entries for recent items. Or if that is not possible, an option to remove all entries in one operation.
Fast forward & reverse:
Complaint: There are no dedicated FFD & REV software buttons but only the finicky/tedious small timeline bar. I also find it too annoying to use the playback speed workaround.
Preference: Tap-hold FFD & REV screen buttons for these operations to advance, for example 10 seconds for each 1 second pressed and gradually increasing in the time advanced the longer the button is pressed. For example, changes to advancing 1 minute per second pressed after being held for about 10 seconds.
As the timeline is small, it is not accurate & precise enough for navigating longer titles. Trying to tap the tip of the finger on the small timeline to advance seconds at a time or reach a specific location is very difficult and tedious.
Prevent device from powering on when connected to the charging cable from an off state:
Complaint: The user does not always want to use the device every time they connect it to charging yet it powers on each time.
Preference: I would prefer that the player simply does not power on when connecting to a charger.
Power off the device using a software alternative to the physical button:
Complaint: If the power button ever fails there is no decent alternative for powering on and off the player. It is instead required to power on the player by plugging it into a USB power source and for powering it off, to enable auto-shutdown after an idle time of 1 minute as a minimum, which interferes with the user's desire to occassionally pause tracks for longer than 1 minute and not desiring to have the player power off, which is does in that setup.
Preference: It would be very helpful if there was a way to immediately power off the player with the press of a software screen button somewhere within the interface instead of enabling auto-shutdown after an idling time of 1 or 5 minutes. In a sense, a software power button as a backup to the physical power button in case it ever fails.
Or instead, maybe something like a 5 second 2 finger press on the sleeping screen to power off the player. Powering the device on from an off state is a different matter because the screen obviously does not have power then. Plugging it into USB power isn't that bad. Or maybe enable the headphone jack to power on the player when headphones are plugged in. Otherwise though, the main concern is being able to immediately power off the player using some sort of screen press if the power button fails, instead of having to wait even for the 1 minute idle time and auto-shutdown.
Of course I would be super excited if all of these requests were fulfilled and I truly believe that all of them are indeed possible, but I would still appreciate it if Shanling (or maybe some Rockbox developers; hopefully someone is working on Rockbox for this great player!

) could at least work on a couple or a few of these!
Thank you Shanling for the great player! It really helps improve my experiences and enjoyment over the Sansa line and is a nice upgrade. And thank you Shanling for reading and at least considering to implement some or all


of these requests! You have such a great, niche player here (for the ultra-compact DAC-DAP lovers). I would highly recommend to take the extra effort and truly polish this device to perfection (or close to it at least)! THANKS!
Clearly my post is lengthy and I don't expect most users to read all of it or even comment. It is mainly here for reference mostly for Shanling or hopefully some sort of Rockbox developer, to make note of what I personally view as areas of the player which could be improved. Shanling or a Rockbox developer may never get around to any of them, maybe not even a single one, but the notes are simply offered here for an area to reference if desired.
