AnalogSteph
Major Contributor
It seems to me that this little player could use a dedicated thread here. @Robin L seems to be one of the few dedicated fans.
With my fleet of Rockboxed Sandisk Sansa Clip+ starting to show their age, I was looking for a replacement, preferably an improved one. Aside from input being partially touch, the FiiO M3K was ticking all the boxes. Rockbox compatibility, MicroSD storage (up to 2 TB), neither microscopic nor a huge brick (anything that does not fit a shirt pocket is automatically out), good battery life, a decent display (2" color IPS, 240x320, with pre-installed glass protector no less), AK4376A DAC / headphone driver with well-documented performance, not breaking the bank (69€ at writing), and if you boot OF you have USB DAC functionality (needs drivers though) and voice recording as well. The Ingenic SoC has 32 MiB worth of RAM built-in, and a MIPS core clocking up to 1 GHz should provide enough oomph to make up for any potential lack of optimized inline assembler code. The outside of the player is protected by asilly cone silicone case right from the factory.
Installing the Rockbox bootloader according to instructions provided is a bit fussy but doable. Tools required on Windows are much the same as what's required for rooting/debranding an Android phone, I think. My new MicroSD card (Samsung MicroSDXC PRO Plus 256 GB, no expense spared) was reformatted to FAT32 using the HP USB Disk Storage Format Tool and an external cardreader.
Theme wise, I settled on Googley-FuzePlus-Clippy, and used the
Performance stats collected so far:
* 0 dBFS (0.9999 FS) output amplitude at volume setting 0 dB: 0.906 Vrms (according to my UT71C TrueRMS multimeter), matching chip spec of 0.57 Vrms at -4 dBFS if you do the math
* Maximum undistorted 0 dBFS output reached at volume setting +2.5 dB, that's pretty much exactly 1.2 Vrms (a.k.a. iPod standard)
* Battery life seems approx. 20 hours with my mix of Amazon MP3 and MP3 LAME -V 4 (way better than a Clip+ with an aging and never very good battery for sure, with a MicroSD card installed that never gave me more than about 10 hours)
* SD throughput via USB: OF 18 MB/s read & 7 MB/s write, Rockbox 12 MB/s read and 6.5 MB/s write. Use a USB3 cardreader for bulk transfers (said Samsung card can write at least 90 MB/s sequentially and will appreciate UHS2 support).
No appreciable noise when using a KZ ZSX IEM of ca. 118 dB / V sensitivity (in line with device spec of <2 µV), just a bit of a click on power-off. The output is DC-coupled and ground-referenced as expected from the AK4376A. USB DAC functionality takes a good while to unmute after playback starts. Rockbox will support sample rates up to 192 kHz with autoswitching but documentation is warning about potential unresponsiveness at 176.4k/192k.
The tactile power / volume / play buttons on the side are good, the capacitive touchpad takes a bit getting used to but is not too bad per se. Taking some time to configure button locking is no doubt worth it. (I turned on autolock, autolock always, and exceptions for the side buttons. Sort of wishing that volume and skip buttons could be swapped, but it's OK as-is. I'd have to compile a RB build myself with a custom key mapping, something I last did 10+ years ago.)
I have yet to measurably verify audio performance but given RMAA results I am fairly confident that it is about as good as they specify (SNR ≥117dB(A-weighted), THD + N <0.004%(1kHz/32Ω), Output impedance<1Ω(32Ω load)). A nice step up from the Clip+ which had been pretty much exactly at 16 bit level DAC wise (95 dB(A) worth of dynamic range on a good day, 1 kHz distortion ~0.0025% when bypassing the mixer, and negligible filter ripple). Perhaps more importantly, the Clip+ also had some audible analog hiss and low-level noises with IEMs - and that had been among the better players in its day. (You can still buy noisier players right now.)
Subjectively, the ZSX sounds a bit smoother on the M3K compared to the Clip+ (maybe due to lower ground return resistance and/or output impedance?), and I slightly tweaked the EQ as follows:
There is some bias due to primarily mobile use, perhaps some loudness as well. This IEM supposedly follows Crinacle's target curve fairly well, I can't say it sounded balanced to me barefoot. Great SQ for the price with a bit of EQ though.
Maximum output has rarely been a problem for me as I tend to be a fairly quiet listener (perhaps 10 dB below average). I was able to just about max out a Clip+ (800 mV max) with HD580s on notoriously dynamic Mahler symphonies, with peaks in the low 90s dB SPL. On the M3K I have set HD580 config default volume at -31 dB, limit at -7 dB. So if you have nothing more demanding than the usual 250/300 ohm Beyerheisers or ATH-R70x' (102-103 dB / V) and normal hearing, I predict the M3K will do just fine. The 50+ semi-deaf club with demanding planars need not apply or should use an amp. This is a normie player for normal headphones, not outrageous excess. Being able to hit 25 mW @ 32 ohms (that's pretty much exactly 0 dBFS at 0 dB, and = chip spec) is respectable enough.
It seems quite fitting to be using a Clip-themed Fuze+ skin on the M3K, as it is sort of a Fuze+ on steroids and replacing a Clip+. Build quality seems rather better though, both my current Clip+' have more or less annoying bugs that I attribute to soldering issues (one has never charged to 100%, the other has an RTC that's running annoyingly fast). Having a full color screen of a decent resolution is obviously a revolution, too (I could fit about 3 lines worth of text on the Clip+), even if the pixel pitch makes a size 8 font unreadable entirely. The backlight is a tad on the bluish side unfortunately and makes one wish for color management facilities, but that's not unusual on inexpensive displays. On the upside, I rarely need to crank up the brightness beyond 50%, and touchpad lighting is plenty adequate at 6%. The display backlight appears to be flicker-free.
Of course it figures that a player that ticks all the boxes apparently is no longer in production. If it's just AKM's outage that was the issue, FiiO could respin the player with the newer AK4377A fairly easily, which has been listed as being back in production for a while now. It seems the designated successor would be the M3 Pro based on an ES9218P and with a full-front touchscreen that came out in 2020 - I don't doubt it's a good player, just no Rockbox port (yet). It seems feasible enough, the biggest obvious hurdles being the DAC (I found a full datasheet at least) and the display.
In any case enough M3Ks seems to be out in the wild for them to remain readily available - at least for now. Once I had verified that it would be fit for purpose, I bought a second one. Better safe than sorry in this day and age.
With my fleet of Rockboxed Sandisk Sansa Clip+ starting to show their age, I was looking for a replacement, preferably an improved one. Aside from input being partially touch, the FiiO M3K was ticking all the boxes. Rockbox compatibility, MicroSD storage (up to 2 TB), neither microscopic nor a huge brick (anything that does not fit a shirt pocket is automatically out), good battery life, a decent display (2" color IPS, 240x320, with pre-installed glass protector no less), AK4376A DAC / headphone driver with well-documented performance, not breaking the bank (69€ at writing), and if you boot OF you have USB DAC functionality (needs drivers though) and voice recording as well. The Ingenic SoC has 32 MiB worth of RAM built-in, and a MIPS core clocking up to 1 GHz should provide enough oomph to make up for any potential lack of optimized inline assembler code. The outside of the player is protected by a
Installing the Rockbox bootloader according to instructions provided is a bit fussy but doable. Tools required on Windows are much the same as what's required for rooting/debranding an Android phone, I think. My new MicroSD card (Samsung MicroSDXC PRO Plus 256 GB, no expense spared) was reformatted to FAT32 using the HP USB Disk Storage Format Tool and an external cardreader.
Theme wise, I settled on Googley-FuzePlus-Clippy, and used the
convttf
utility now provided among existing font downloads to make a version of the GNU Unifont in a size I can actually read (24 with -c 2). Not the prettiest font (the numerals rather suck) but without CJK support I am SOL. This is an ongoing battle.Performance stats collected so far:
* 0 dBFS (0.9999 FS) output amplitude at volume setting 0 dB: 0.906 Vrms (according to my UT71C TrueRMS multimeter), matching chip spec of 0.57 Vrms at -4 dBFS if you do the math
* Maximum undistorted 0 dBFS output reached at volume setting +2.5 dB, that's pretty much exactly 1.2 Vrms (a.k.a. iPod standard)
* Battery life seems approx. 20 hours with my mix of Amazon MP3 and MP3 LAME -V 4 (way better than a Clip+ with an aging and never very good battery for sure, with a MicroSD card installed that never gave me more than about 10 hours)
* SD throughput via USB: OF 18 MB/s read & 7 MB/s write, Rockbox 12 MB/s read and 6.5 MB/s write. Use a USB3 cardreader for bulk transfers (said Samsung card can write at least 90 MB/s sequentially and will appreciate UHS2 support).
No appreciable noise when using a KZ ZSX IEM of ca. 118 dB / V sensitivity (in line with device spec of <2 µV), just a bit of a click on power-off. The output is DC-coupled and ground-referenced as expected from the AK4376A. USB DAC functionality takes a good while to unmute after playback starts. Rockbox will support sample rates up to 192 kHz with autoswitching but documentation is warning about potential unresponsiveness at 176.4k/192k.
The tactile power / volume / play buttons on the side are good, the capacitive touchpad takes a bit getting used to but is not too bad per se. Taking some time to configure button locking is no doubt worth it. (I turned on autolock, autolock always, and exceptions for the side buttons. Sort of wishing that volume and skip buttons could be swapped, but it's OK as-is. I'd have to compile a RB build myself with a custom key mapping, something I last did 10+ years ago.)
I have yet to measurably verify audio performance but given RMAA results I am fairly confident that it is about as good as they specify (SNR ≥117dB(A-weighted), THD + N <0.004%(1kHz/32Ω), Output impedance<1Ω(32Ω load)). A nice step up from the Clip+ which had been pretty much exactly at 16 bit level DAC wise (95 dB(A) worth of dynamic range on a good day, 1 kHz distortion ~0.0025% when bypassing the mixer, and negligible filter ripple). Perhaps more importantly, the Clip+ also had some audible analog hiss and low-level noises with IEMs - and that had been among the better players in its day. (You can still buy noisier players right now.)
Subjectively, the ZSX sounds a bit smoother on the M3K compared to the Clip+ (maybe due to lower ground return resistance and/or output impedance?), and I slightly tweaked the EQ as follows:
Code:
eq enabled: on
eq precut: 45
eq low shelf filter: 710, 7, 45
eq peak filter 1: 64, 10, 0
eq peak filter 2: 125, 10, 0
eq peak filter 3: 250, 10, 0
eq peak filter 4: 500, 10, 0
eq peak filter 5: 750, 5, 30
eq peak filter 6: 2000, 10, 0
eq peak filter 7: 6000, 5, 0
eq peak filter 8: 8000, 10, 0
eq high shelf filter: 3000, 10, -15
Maximum output has rarely been a problem for me as I tend to be a fairly quiet listener (perhaps 10 dB below average). I was able to just about max out a Clip+ (800 mV max) with HD580s on notoriously dynamic Mahler symphonies, with peaks in the low 90s dB SPL. On the M3K I have set HD580 config default volume at -31 dB, limit at -7 dB. So if you have nothing more demanding than the usual 250/300 ohm Beyerheisers or ATH-R70x' (102-103 dB / V) and normal hearing, I predict the M3K will do just fine. The 50+ semi-deaf club with demanding planars need not apply or should use an amp. This is a normie player for normal headphones, not outrageous excess. Being able to hit 25 mW @ 32 ohms (that's pretty much exactly 0 dBFS at 0 dB, and = chip spec) is respectable enough.
It seems quite fitting to be using a Clip-themed Fuze+ skin on the M3K, as it is sort of a Fuze+ on steroids and replacing a Clip+. Build quality seems rather better though, both my current Clip+' have more or less annoying bugs that I attribute to soldering issues (one has never charged to 100%, the other has an RTC that's running annoyingly fast). Having a full color screen of a decent resolution is obviously a revolution, too (I could fit about 3 lines worth of text on the Clip+), even if the pixel pitch makes a size 8 font unreadable entirely. The backlight is a tad on the bluish side unfortunately and makes one wish for color management facilities, but that's not unusual on inexpensive displays. On the upside, I rarely need to crank up the brightness beyond 50%, and touchpad lighting is plenty adequate at 6%. The display backlight appears to be flicker-free.
Of course it figures that a player that ticks all the boxes apparently is no longer in production. If it's just AKM's outage that was the issue, FiiO could respin the player with the newer AK4377A fairly easily, which has been listed as being back in production for a while now. It seems the designated successor would be the M3 Pro based on an ES9218P and with a full-front touchscreen that came out in 2020 - I don't doubt it's a good player, just no Rockbox port (yet). It seems feasible enough, the biggest obvious hurdles being the DAC (I found a full datasheet at least) and the display.
In any case enough M3Ks seems to be out in the wild for them to remain readily available - at least for now. Once I had verified that it would be fit for purpose, I bought a second one. Better safe than sorry in this day and age.
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