Root and TWRP for M15, M11Pro, M11

More detail and full translation.

0. Root rights are needed to be able to do something in the Android system partition. This is needed to: remove unnecessary system applications; changes to sound processing libraries; replacement of different versions of the pre-installed FiiO Music player.
There is no danger in this operation for the player. You can always undo the changes and re-flash the version of the stock firmware you need (both the latest and earlier).

1. Launching the patch:
1.1. Download the file to the player's internal memory or any other folder in the internal memory or SD card.
1.2. Reboot into Recovery : boot while pressing [ Power ] + [ Next track ].
1.3. In Recovery, go through the items with [ Next / Prev track ], apply the menu item with [ Power ].
1.4. Find the patch file in the file system and run it - the wizard screens appear with explanations in Russian.

2. Features of the patch:
2.1. If you do not check any menu item and apply the patch, the ramdisk section will be changed, root-rights will be obtained, but there will be no visual interface for working with them.
2.2. Magisk Manager v301 is just a visual interface program for working with root rights. This must be set!
2.3. Mixplorer v6.49.3 is a powerful and easy-to-use file manager that uses root-rights capabilities. Set as desired. The firmware is preinstalled with ES Explorer, which can also work with root.
2.4. EsFileManager v4.2.3.1. - a more recent version of the file manager preinstalled in the firmware, working with root. Update as desired.
2.5. Format Data / Cash - bringing your firmware back to its original state, all changes will be canceled, all third-party applications and music in the internal memory will be erased (everything will remain on the SD card). This is the same "reset" from the Player Settings.
2.6. Ainur Narsil is a package for changing audio processing libraries in Android. Turns off almost everything that is possible, which favorably affects the transparency and dynamics of the sound. Official site: ainuraudio.ru The same module can be installed from the Magisk Manager menu, there it can be temporarily disabled and removed. I advise you to install not from here, but from Magisk Manager.
2.7. FM v3.0.0 beta (c lib from 20200623) - almost the final version of FiiO Music 3.0 with an updated interface, published the other day. This version replaces libraries with libraries from FM beta-20200623 , which, in my opinion, has the best sound.
FM will be installed as a system, that is, you cannot remove it in the usual way.
2.8. FM v1.2.0 20200623 beta - the same version beta-20200623 with "the best sound". In my opinion, the sound is even superior to the FM sound from the previous paragraph (apparently, it's not only the libs, but also the code). The interface is the same (now old), but the functionality is essentially the same. I have been using this version for a long time.
FM will be installed as a system, that is, you cannot remove it in the usual way.
2.9. Removing FiiOMusic - preset FM is removed from the system partition. After downloading, the player will not have FiiO Music at all. You can install any version of FM in the usual way for Android, as a custom application. And remove it accordingly. Including you can deliver the latest FM 3.0, published at the office. site. This setting does not affect the sound or functionality in any way.
I use FM exactly like a custom application.

3. Click " Next ", apply the patch and reboot.

4. At any stage of the selection, you can click in the bottom line " vertical 3 dots " and through the menu that appears, exit the installation process.


A few more links:
* FM beta_20200623 , which can be installed as a custom application, the best sound (IMHO):
yadi.sk/d/jQdqL9fN-x4bjA

* FM 3.0 is the official version for Android from the office. site, which, so far, many cannot put on the player:
http: //fiio-file.fiio.....sic%20Android3.3.0.apk
Now you can remove the system FM with a patch and install it.

This is nice. I'm still trying to sell my M11 Pro and in the meanwhile I discovered its fastboot mode, but I'm not using it anymore. This could've been interesting.

Ooohhh!! Awesome sauce!!