Today, James reviews the FiiO K17, a new retro-inspired desktop dual DAC and balanced 4000mW capable headphone amplifier with Bluetooth support. It is priced at $899.
Disclaimer: I received this sample in exchange for my honest opinion. Headfonics is an independent website with no affiliate links or services. I thank FiiO for their support.
You can click here to learn more about the FiiO audio products previously reviewed on Headfonics.
This post follows our current scoring guidelines, which you can read in more detail here.
The new $899 FiiO K17 is an integrated decoder and streamer and the successor to the K9 Pro series of desktop amp/DACs.
Similar to the full-size S15 streamer or the flagship K19 amplifier, the K17 has some unique features, such as local playback and a new innovative touch-capable control interface.
This is a cool retro-designed piece of gear that functions with much more versatility than expected. To highlight its key strengths, the K17 is a great match with FiiO headphones such as the FT5 and various 3rd party open-back designs due to its full-bodied tuning.
This is one of the most attractive designs from FiiO to date, but how does it stack up against the older K9 Pro ESS and the flagship K19? I found out in my full review below.
Features
The K17 features a lot of physical knobs and a big screen to display current modes and settings. Inside the retro and techno-styled housing, FiiO uses an AK4191 and AK4499EX*2 DAC combo.
It is capable of decoding up to native DSD512 and 32bit/768kHz in its USB-DAC/amp mode and can playback local files at 384kHz/32bit and DSD256 via a USB-A port at the back for flash drives and powered hard drives.
The amplification is a discreet design instead of THX 788+ and is based on OP + transistor current amplification featuring the ON Semiconductor MJE243/253 transistors.
This is a design for high current output with low output impedance and can deliver up to 4000mW output power per channel in its balanced output.
The fully balanced decoding and amping design also features 3 ultra-low phase noise femtosecond oscillators and a linear PSU rated 35W.
Another important feature is the 31-band parametric equalizer as featured on the K19, powered by the M21586Q DSP chipset and an ES9821Q ADC dedicated to this section.
Design
So far, this is one of the most appealing designs from FiiO, not only because of the cool and sleek retro style but also because the UX that is friendlier than on the K19, as you can very intuitively use the knobs to switch between modes on the device within a sec or two.
The K17 comes in two colors, a lighter silver and more discreet black, with my sample in black. Either color compliments the vintage color scheme on the 3.93” touch screen.
There are some openings on the top and sides which makes it looks cooler, though its still very FiiO to have avolume/multi-function knob with a ring of LED around it that matches the theme color. All of these accents look very cool, even in the dark.
Also, more nuanced etails such as the markings and the small red-light dot on the on/off button indicating power is connected, as well as the smooth feedback when twisting the knob give the K17 a very satisfactory visual and tactile user experience.
I/O
On the front side, you will find 6.3mm, 4.4mm, and XLR outputs. There is also a USB-C socket to connect to other USB sources without needing to reach around to the back of the device.
The I/O design is quite similar to the K19, and on this set, you will even find 4.4mm and RCA line-in sockets to use the K17 as an analogue amplifier or pre-amp, which differentiates it from the K19.
As usual, it supports coaxial and optical in/output, RCA and BAL XLR out, a ground-loop breaking switch, an antenna jack, and USB and LAN sockets.
Controls
With plenty of knobs plus a touch screen, the UX gets even more intuitive on this one as the key functions and connectivity can all be controlled without accessing menus.
With the physical knobs, you can toggle on/off, change between PO, pre-amp and LO, also switching between different gain levels. The settings are displayed on the status bar on the screen and come into effect immediately.
The multifunction knob is similar to the one on K19 or the S15, which would allow users to access detailed settings, and the volume knob on the right is well stepped for fine output level control.
The touch screen allows you to select different modes, EQ, and other settings, including changing the theme, configuring the trigger-in option, and controlling local playback.
You can swipe up and down to select display themes after future upgrades and swipe left and right between settings and various functions.
You can also use the remote control in the package, which is handy for switching between songs and for volume control when listening over on the sofa across the living room.
Local Playback
Since this is not an obvious and usual feature for a decoder/streamer, I am bringing it up here again. You can plug a USB-thumb drive or a powered hard drive to the K17 and playback local files.
This is a great feature, considering you can fire up the K17 and play some songs without the need to hook it up to a player or a PC. However, please remember to upgrade to the latest firmware for cover art display and more tagging options.
PMEQ
The K17 comes with 31-band high-precision lossless PMEQ operating at a high 360MHz clock speed and based on 64-bit floating point calculation, just like the K19.
This allows accurate tuning to fix room acoustic issues or alter the output curve of gears being paired with it. As expected, the feature can bypass SRC for PCM signals and be applied globally.
To further enhance the PMEQ performance, this section is paired with an additional ES9821Q ADC and a custom ultra-low phase noise femtosecond crystal oscillator.
Users can download the control UI for tweaking the equalizer on Mac or Windows PC, connected via the RS232 port USB connection. The tuned profile can then be saved on the device and on the PC for sharing.
Wireless Connectivity
Bluetooth 5.1
The K17 has a similar antenna design to the K19 and R9, with the QCC5125 chipsets inside. It supports aptX HD/aptX Adaptive/LDAC codecs that can be chosen for various usage scenarios.
For gaming or video content, I prefer to use aptX Adaptive whenever possible, but LDAC provides higher quality and a fuller sound over a shorter transmitting distance.
WiFi
The K17 is designed to be Roon Ready with Airplay support. Simply hook it up to your home network, and you can select the K17 as an output device. The experience is similar to other FiiO devices that support Airplay and is pretty similar to Bluetooth connection in terms of delay.
Another merit for Airplay over Bluetooth is that the cover art will also be displayed, which feels much cooler. And if you are tied to Bluetooth only, then I recommend to swipe to the VU meter visualizer.
Wired Connectivity
You can hook up your Laptop, iPad, or other audio devices that support USB audio output straight to the USB socket on the front panel of the K17.
No USB driver is required for Mac users, but for older versions of Windows, you will need to download it from the FiiO website.
Do note that if you connect devices to both of the USB ports at the same time, the one in the front panel will be prioritized, and the one at the back will be temporarily disabled.
Packaging & Accessories
The K17 comes in a foam padded box with a plastic handle, similar to those when you buy a 24” computer screen at home.
Inside the box, there is an infrared remote, an extra fuse, two USB A to C cables, a 6.3mm to 3.5mm convertor, and a dust cover for the balanced XLR output.
Since there is a USB-C port on the front panel, it would be nicer if one of those USB cables could be swapped for a USB C-C one.
Sound Impressions
I gave the K17 a week of run-in time with a USB source, mainly using its balanced output, which is the most powerful output for headphones.
In the below test, I paired the K17 with headphones such as the FiiO FT5, MOONDROP COSMO, Meze Audio 105 AER, Sennheiser HD 800s, the Palma DHS-1, and some IEMs to see how it synergizes with gears with different powering requirements.
Summary
Positioned between the K9 Pro ESS and K19, the K17 switches from THX amplification to discreet circuitry and 4000mW max output per channel, giving it plenty of power for various headphones.
It sounds dynamic, with plenty of headroom while maintaining good tonal balance and resolution alongside an otherwise full-bodied presentation.
Unlike the cleaner sounding K19, the K17 is more intimate than neutral across the mids. It puts more stress on the treble on the higher gain modes while sounding fuller in bass and quite rounded in treble with the lower gain levels.
Timbre
I have tried various gears using the AK4191EQ and dual AK4499EX combo, which leaves a consistent impression that is refined yet rich and dense in the mids. The K17 is no exception, but it also maintains a swift response in the mids, asd well as good separation and weight for instruments and vocals
There are some big 4700uf caps implemented, and this is possibly the reason why the bass on the K17 punches deep and recovers with great agility. It also helps shape an impactful, airy, and extended soundscape. When the BPM is fast, the bass impact sounds powerful and articulate.
With easier to drive headphones such as the Palma DHS-1, the K17 sounds revealing, with good brilliance in the treble on high gain and quite rounded on lower gain levels.
I find the high gain level adequate, balancing dynamics and vocal transparency. When pushed to the highest gain level, the vocal level is more upfront, yet the dynamic range is slightly suppressed, possibly due to the high sensitivity of these headphones.
Some quick tweaks with PMEQ to bring up the fundamental bass frequencies for better tonal balance would help it sound much more euphonic.
Testing with the FiiO FT5, which has thicker and more powerful bass, I get a more balanced sound, working nicely with the higher gain modes to sound airy and impactful in the lower end while delivering pronounced yet rounded vocals.
Gain Levels
Pushing to higher gain levels, the bass attacks firmer, and the treble gets sharper. It sounds more exciting with woodwinds and violin solos by stressing the transients and doesn’t get over the edge to sound piercing.
This works well with open-back headphones such as the HD 800s, particularly with Classical music, brass instruments, and male vocals, which sounds well separated from the mix and has sufficient penetration power and brilliance but with the sibilance zone dimmed.
In this sense, tweaking the 5 gain levels with the knob on the fun panel could be an easy way to switch between a softer, warmer timbre, or to make it more aggressive, cleaner at higher gain levels.
The resolution, on the other hand, is satisfactory, with mid-bass having sufficient weight and power so it works pretty well with various genres. The slightly warmish tuning is great for vocal works and solos and when playing higher bit-rate masters.
Staging & Dynamics
Being more rounded than the K19 in the upper end and bumping up the mid-bass gently, the K17 has a more intimate stage rendered, yet there is sufficient layering and depth in space to make it structured, layered, and moderately expansive.
It sounds energized in the low end, which is great for live recordings. The perceived space is akin to the size of a lecture hall that is nicely dampened.
The warmth also helps planar headphones to sound more holographic, darker, and more layered in the mids, and higher impedance cans can make use of stronger gain levels to sound more opened and enhance vocal penetration power.
The tuning is sweetening vocals, but at the same time, it takes away some air, so if you want it to sound more exciting and airy, PMEQ could be of good help.
Transients performance on the K17 is also decent, which helps define instrument positioning clearer. At the highest gain mode, more details can be heard for strings, trumpets, and woodwinds, and the vocal position is clearer. Whereas on lower gain levels, it sounds less defined.
Click on page 2 below for my recommended pairings and selected comparisons.
