I won't really dig into the FiiO M5's plethora of wired and wireless features but mainly concentrate on its performance as a traditional digital audio player.
Available in multiple colours.
Back is made of glass.
Decent build quality.
Rather small buttons, however easy to find and distinguish. No volume up/down (+/-) indicator except for a tactile dot on the volume up button.
Fairly small and compact - not as slim as my Apple iPod Nano 6G, but still nicely compact.
Surprisingly heavy for the size.
Nice blue LED above the screen (for Bluetooth-related stuff).
Does not seem to support cable remote commands.
No screen protector applied by factory, which is not very FiiO-like. Two protectors and a data/charging cable are included, though, along with a plastic case with integrated clip.
Bluetooth and stuff (can send and receive Bluetooth audio streams (both in aptX and other codecs)).
USB DAC in- and output.
Built-in microphones (can be used for hands-free phone calls when the player is connected to a mobile phone via Bluetooth) and built-in voice recorder.
Built-in step counter.
USB-C (USB 2.0).
Combined headphone, line and coaxial output socket.
1.54 inch 240 x 240 pixels touchscreen (similar screen dimensions and resolution as my iPod Nano 6G). Easy to read and doesn't feel pixelated at all despite the seemingly low resolution.
Very unfortunately, it does not have a built-in FM radio.
No internal storage.
The screen orientation can be changed, however, unlike on my Apple iPod Nano 6G, only through the settings and not through intuitive two-finger turns.
What's somewhat annoying: the 3.5 mm socket is located right next to the volume control buttons, wherefore operating them while a headphone/in-ear with an angled plug is inserted is only possible when the plug is turned into the other direction. The same goes for thick plugs. That's definitely better executed on my Apple iPod Nano 6G where the 3.5 mm socket and control buttons are on opposite sides.
- - -
The optional SK-M5 silicone watch-/wristband is made of soft, black silicone. However, the part where the M5 goes in is quite thin and wobbly, so it doesn't appear very sturdy or tearproof for long-term use. There's no cutout for the USB socket or the 3.5 mm output (there are two holes for the two microphones, though).
One also needs to consider that the M5 is quite thick on the wrist, so it's less ideal as an everyday smartwatch but more as a digital Bluetooth streaming source that's easy to access on one's wrist to control the playback of Bluetooth headphones or Bluetooth speakers.
Available in multiple colours.
Back is made of glass.
Decent build quality.
Rather small buttons, however easy to find and distinguish. No volume up/down (+/-) indicator except for a tactile dot on the volume up button.
Fairly small and compact - not as slim as my Apple iPod Nano 6G, but still nicely compact.
Surprisingly heavy for the size.
Nice blue LED above the screen (for Bluetooth-related stuff).
Does not seem to support cable remote commands.
No screen protector applied by factory, which is not very FiiO-like. Two protectors and a data/charging cable are included, though, along with a plastic case with integrated clip.
Bluetooth and stuff (can send and receive Bluetooth audio streams (both in aptX and other codecs)).
USB DAC in- and output.
Built-in microphones (can be used for hands-free phone calls when the player is connected to a mobile phone via Bluetooth) and built-in voice recorder.
Built-in step counter.
USB-C (USB 2.0).
Combined headphone, line and coaxial output socket.
1.54 inch 240 x 240 pixels touchscreen (similar screen dimensions and resolution as my iPod Nano 6G). Easy to read and doesn't feel pixelated at all despite the seemingly low resolution.
Very unfortunately, it does not have a built-in FM radio.
No internal storage.
The screen orientation can be changed, however, unlike on my Apple iPod Nano 6G, only through the settings and not through intuitive two-finger turns.
What's somewhat annoying: the 3.5 mm socket is located right next to the volume control buttons, wherefore operating them while a headphone/in-ear with an angled plug is inserted is only possible when the plug is turned into the other direction. The same goes for thick plugs. That's definitely better executed on my Apple iPod Nano 6G where the 3.5 mm socket and control buttons are on opposite sides.
- - -
The optional SK-M5 silicone watch-/wristband is made of soft, black silicone. However, the part where the M5 goes in is quite thin and wobbly, so it doesn't appear very sturdy or tearproof for long-term use. There's no cutout for the USB socket or the 3.5 mm output (there are two holes for the two microphones, though).
One also needs to consider that the M5 is quite thick on the wrist, so it's less ideal as an everyday smartwatch but more as a digital Bluetooth streaming source that's easy to access on one's wrist to control the playback of Bluetooth headphones or Bluetooth speakers.
GUI:
Surprisingly intuitive navigation by swipe gestures - a lot like on my Apple iPod Nano 6G, but not entirely similar (e.g. no long press return to home screen). One can go back by swiping from left to right - just like on my iPod Nano 6G.
Swiping from top to bottom and then clicking on the album cover/title/interpret display jumps straight to the playback screen where one can swipe left and right to access different playback-related screens.
Smooth and fluent navigation and animations.
Navigation (clicking on specific elements and swiping from left to right to go back) not always as precise as on my Apple iPod Nano 6G or 7G, however good most of the time.
Currently (FW 1.2.0), some playback-related bugs (long track title texts aren't fully displayed and don't scroll automatically/cannot be scrolled horizontally by swiping over them) still persist.
Currently no volume indicator on the lock screen or playback screen or drop-down playback screen (only in the menus); only pops up when changing the volume.
Typical FiiO feature (that I also already know from my X3): "Resume mode": "Position" leads to the playback to continue right after the player is turned on again, and there is no option to having to click on "play" manually (that's what I like about the Rockbox firmware on my SanDisk Sansa Clip Plus, Sansa Clip Zip and the xDuoo X3 - it leaves the user the option to continue the playback automatically after booting the player or to having to click on "play" manually in order for the playback to start).
Swiping from top to bottom and then clicking on the album cover/title/interpret display jumps straight to the playback screen where one can swipe left and right to access different playback-related screens.
Smooth and fluent navigation and animations.
Navigation (clicking on specific elements and swiping from left to right to go back) not always as precise as on my Apple iPod Nano 6G or 7G, however good most of the time.
Currently (FW 1.2.0), some playback-related bugs (long track title texts aren't fully displayed and don't scroll automatically/cannot be scrolled horizontally by swiping over them) still persist.
Currently no volume indicator on the lock screen or playback screen or drop-down playback screen (only in the menus); only pops up when changing the volume.
Typical FiiO feature (that I also already know from my X3): "Resume mode": "Position" leads to the playback to continue right after the player is turned on again, and there is no option to having to click on "play" manually (that's what I like about the Rockbox firmware on my SanDisk Sansa Clip Plus, Sansa Clip Zip and the xDuoo X3 - it leaves the user the option to continue the playback automatically after booting the player or to having to click on "play" manually in order for the playback to start).
Sound:
Nice: no glitches/pops/crackle/thump when inserting/removing the headphone plug.
Gentle fade in/out when pressing play/pause. Gentle fading as well when changing the volume setting.
Currently (FW 1.2.0), when using high sensitivity, low impedance in-ears, very often, there is some mild left channel crackle/pop when pausing/skipping/changing the playback position of most files and during the transition of two files (this, the latter, mainly on lossy files, however the rest also happens very often (in almost all cases (click/pop/crackle is always present when changing the playback position or when pausing/resuming the playback/muting/unmuting the volume regardless of whether the file is lossy or lossless)) when playing lossless files), and it can even happen in a silent passage of a song; so it seems to be some sort of totally unnecessary noise gate that immediately turns off the amplifier section when no signal is detected. No idea whether it could be solved by a software update or not, but it is definitely highly annoying.
Gentle fade in/out when pressing play/pause. Gentle fading as well when changing the volume setting.
Currently (FW 1.2.0), when using high sensitivity, low impedance in-ears, very often, there is some mild left channel crackle/pop when pausing/skipping/changing the playback position of most files and during the transition of two files (this, the latter, mainly on lossy files, however the rest also happens very often (in almost all cases (click/pop/crackle is always present when changing the playback position or when pausing/resuming the playback/muting/unmuting the volume regardless of whether the file is lossy or lossless)) when playing lossless files), and it can even happen in a silent passage of a song; so it seems to be some sort of totally unnecessary noise gate that immediately turns off the amplifier section when no signal is detected. No idea whether it could be solved by a software update or not, but it is definitely highly annoying.
Volume Control:
60 volume steps (no gain setting). Gentle fading up/down when changing the volume (therefore no instant volume changes), which is definitely a matter of taste (I, and I assume most people as well, prefer a direct volume control response, but the fading in and out is nonetheless pleasant as well, however somewhat irritating, too, as it takes around one second for the volume to change after pressing any of the two volume buttons).
Even using extremely sensitive in-ears such as my Campfire Audio Andromeda and playing loudly mastered files, the lowest possible volume setting above mute is quiet enough for me for quiet listening, which is very, very good.
Personally, I wouldn't mind more steps than 60 in order to achieve finer volume steps changes (that's my criticism about every device that doesn't have 1 db to 0.5 dB changes over the entire adjustable range), but the jumps aren't too big even in the low adjustable range, so it's fine.
Gapless Playback:
Works perfectly using FLAC files.
Even using extremely sensitive in-ears such as my Campfire Audio Andromeda and playing loudly mastered files, the lowest possible volume setting above mute is quiet enough for me for quiet listening, which is very, very good.
Personally, I wouldn't mind more steps than 60 in order to achieve finer volume steps changes (that's my criticism about every device that doesn't have 1 db to 0.5 dB changes over the entire adjustable range), but the jumps aren't too big even in the low adjustable range, so it's fine.
Gapless Playback:
Works perfectly using FLAC files.
Frequency Response (no Load):
Very good; just as flat as it should be.
Output
Impedance / complex Load Frequency Response/Frequency Deviation (Load: Ultimate
Ears Triple.Fi 10):
The very small deviation indicates that FiiO's stated specs of a very low output impedance of below 0.5 Ohms are quite plausible.
Hiss Performance:
Using my extremely sensitive Campfire Audio Andromeda, the audible hiss in a very quiet but not yet silent passage of a song is only slightly audible in a quiet room, which makes the M5 very good/almost perfectly perfect in this regard. Therefore it is one of those very rare low output impedance devices with very good hiss performance using extremely sensitive in-ears.
Subjective Sound Perception (3.5 mm Headphone Output):
The M5's specs are very good and so is its measured performance, therefore it is no surprise at all that its sound is subjectively clean and transparent, "precise", as it should be the case for a flawless modern audio device.
Subjectively, using well-resolving multi-BA in-ears, I have the slight subjective feeling that the bass response may be a little softer compared to other devices such as my RME ADI-2 DAC or iBasso DX90, but even if it were the case, it were just one of those minor and practically irrelevant differences even in concentrated listening real-world scenarios.
Subjectively, using well-resolving multi-BA in-ears, I have the slight subjective feeling that the bass response may be a little softer compared to other devices such as my RME ADI-2 DAC or iBasso DX90, but even if it were the case, it were just one of those minor and practically irrelevant differences even in concentrated listening real-world scenarios.
Conclusion:
Theoretically very good nearing perfect when it comes to audio performance (especially in regards to its low output impedance and very good hiss performance), but with some annoying flaws when using really high sensitivity in-ears.