I've used this player for a few months, I added Rockbox to it and set it up for dual boot. If you don't want Rockbox, I'll be happy to reset it and make FIIO only.
If you want to keep both boot options and want to change the micro SD card for a larger one, just copy paste both files from the included 32GB card into the new one, see last photo for files.
Note this player has no internal storage, it needs an micro SD card; I have used it with the included 32GB, a 64GB one and, more recently, I was using it with a 512GB SD card with no problems. Some people on the web said it should support up to 2TB SD cards but I did not try it.
The current boots work as follows: Rockbox, just turn it on and it goes into Rockbox; for the stock firmware, simultaneously press the play button and the on button and it will go to the FIIO firmware.
If you want more info on Rockbox, you can find it at Rockbox dot org. Among other things, it adds support for Flac files, extra EQ functions, and better battery performance :-)
A bit of description from the eBay AI and from the web :-)
The Fiio M3k High Resolution Audio Player is a versatile device offering dual boot functionality with both Android and iOS operating systems. This sleek silver device supports various playable media formats including MP4, MP3, and MP5. The inclusion of an SD memory slot further enhances its storage capabilities, making it ideal for music lovers looking for a high-quality portable audio player. The Fiio M3k model from FiiO delivers exceptional sound quality and convenience in a compact design.
FiiO M3K Portable High Resolution Music Player MP3 Player with Digital Voice Recorder
FiiO have now given us the most cost-effective portable music player the FiiO M3K. Mastering quality lossless playback at an affordable rate. FiiO have taken the M3 and updated everything. Introducing standby mode, updated body clock/date display, higher memory and supporting most file types. The FiiO M3K Portable High Resolution Music Player is encased in aluminium alloy and spots a conductive touch panel beneath a full laminated tempered glass for user interactivity. Allowing one-handed control with its slim body and easy interface and touchscreen. Internal Discreet high performing DAC AK4376A Ingenic X1000E SoC Support Spotting an AK4376A DAC from AKM the M3K adds playback support for a wide range of file formats. Up to 512GB via Micro SD card with a maximum sampling rate of up to 384kHz/32-bit up from 96kHz/24-bit offered by its predecessor. Noise floor FiiO technical capabilities are demonstrated by the audio performance improvements it has achieved with the M3K over its predecessor most notably increasing the SNR to 117 dB from 95dB which is key to reducing the noise floor from just 10uV to 2uV as well as a reduction in distortion from 0.008% to 0.004%. Battery life With a battery life of 26 hours from its 1100mAh built-in battery the M3K succeeds its predecessor as the offering with the longest battery life in FiOS DAP product line. FiiO also added the standby functionality which allows the player to operate in an ultra-low-power idle state for up to 38 days without having to switch the player off a functionality previously not available on the M3. FiiO has added a built-in microphone to the M3K with a recording function allowing the DAP to also function as a digital voice recorder.
- FiiO M3K Mini HiFi Metal Shell MP3 Player with Digital Voice Recorder,
- 24 Hours Playback, 1100mAh built-in battery
- Expandable Up to 512GB
- Discreet high performing DAC, AK4376A DAC
