I Tried the FiiO K19 and Found More Than 31 Reasons Why It’s Great!

When placed upright the K19 looks unique and works as a nice headphone stand. (From: Rudolfs Putnins)
When placed upright the K19 looks unique and works as a nice headphone stand. (From: Rudolfs Putnins)

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FiiO’s flagship DAC/amp offers industry-leading DSP powers and great baseline sound quality.

FiiO K19

(88%)
Our Review Guidelines ⧉
Evaluated over: 8 weeks
Bottom Line

Anyone who enjoys EQing headphones will love the FiiO K19. Its vast DSP capabilities are unmatched by any audiophile hardware. Even without DSP, the sound quality is great for the price. Unlike EQ apps that can burden your CPU or introduce latency, the K19 adds easy profile switching with a remote click. Despite needing some software UX fixes, the K19 is FiiO’s best effort to date, offering high-quality sound in a sleek, fresh package.

Form
Desktop DAC/amp
DAC Chipset
2xES9039S PRO
Balanced Output
4.4mm, XLR
Max Output Power
8000 mW
BT Version
5.1
Weight
1800 g
What We Like 😍
  • 31 PEQ bands are more than enough for anything
  • Great implementation of the ESS flagship chip
  • The upright stand is a godsend for some desks
  • Enough power for anything and quiet enough for IEMs
  • A smorgasbord of I/O options
What We Don't Like 🤢
  • DSP controls can be improved
  • The tiny screen limits operation at a distance
  • In-device menus need work
  • DSP is only applied to analog outputs
  • No lossless Bluetooth
Thank you to FiiO for providing the K19 DAC/amp for review purposes.

During the last year or so reviewing amps and DACs from SMSL, FiiO, and others, I’ve generally been happy with their performance but have wondered where the so-called Chi-Fi will go if they want to conquer the higher price bracket. Almost all products follow well-proven opamp-based designs which show stellar measured performance.

Many listeners will look for something special when venturing into the over-kilobuck price range. After all, even USD $100 stuff can handily show numbers well below the audible threshold. FiiO’s approach with the K19 DAC/amp is to go all-out with DSP and create a do-it-all box that’s the perfect core of any audio system.

Are 31 parametric EQ bands enough to tug on my heartstrings and is the K19 something more than just a curve jockey’s dream? Read on to find out!

Design and Build

The FiiO K19’s basic form factor is a 1U-thick, not-quite-half-width rack unit. FiiO has designed the K19 to be equally at home in a horizontal or vertical position. It comes with bolt-on bracket feet that keep it surprisingly steady when upright.

Man typographical design elements use FiiO's mecha aesthetic. (From: Rudolfs Putnins)
Man typographical design elements use FiiO’s mecha aesthetic. (From: Rudolfs Putnins)

Both the top and bottom sides have CNC-cut honeycomb openings which aid cooling. Below them is a metal mesh that keeps the dust bunnies out. During operation, the K19 doesn’t get too warm unless you keep it on its side, which reduces the airflow a bit.

The honeycomb structure aids in cooling the packed device. (From: Rudolfs Putnins)
The honeycomb structure aids in cooling the packed device. (From: Rudolfs Putnins)

The front panel of the K19 houses four connections – 4-pin XLR, 6.35mm TRS, 4.4mm jacks for headphones, and a front USB-C for connecting your smartphone. All three headphone jacks are live, and you can potentially use three headphones simultaneously. There are two encoder knobs. One is a dedicated volume controller and the second is for controlling the menus.

Navigating the menu on the K19 is a tad clunky. (From: Rudolfs Putnins)
Navigating the menu on the K19 is a tad clunky. (From: Rudolfs Putnins)
There’s also a small-ish 1.30” TFT screen which is okay for desktop use, though difficult to see from a distance.

Bluetooth

The K19 uses the tried-and-tested QCC5125 receiver, which supports version 5.1 communications. Therefore, we have the usual bevy of lossy codecs: AAC, SBC, aptX, aptX LL, aptX Adaptive, aptX HD, and LDAC.

The K19 takes HDMI signal from all TVs, the black plastic box houses the Bluetooth antenna. (From: Rudolfs Putnins)
The K19 takes HDMI signal from all TVs, the black plastic box houses the Bluetooth antenna. (From: Rudolfs Putnins)

While I don’t feel too miffed about the exclusion of the newest lossless codecs, a flagship ought to have some future-proofing. The phones that support it have been slowly entering the market for about a year now.

Controls

You control the K19 in two ways: the front panel encoder knob does in-depth adjustments, and the remote is for changing the volume and IO config. In total there are six inputs to select:

  • USB (the front panel input is prioritized)
  • Coaxial
  • Optical
  • HDMI
  • HDMI-ARC
  • Bluetooth
The IO on the K19 is crazy. I just wish they would use BNC for SPDIF. (From: Rudolfs Putnins)
The IO on the K19 is crazy. I just wish they would use BNC for SPDIF. (From: Rudolfs Putnins)

There are four output modes which can be easily switched by the remote:

  • PO: headphone drive
  • PRE+PO: headphone and line-outs
  • PRE: only line-outs with adjustable volume
  • LO: line-outs driven with fixed 4.8Vrms

While I appreciate the options, the volume settings stay the same. It would be better if the preamp mode could memorize its own volume and then use the DSP settings for easier switching.

You can power the K19 from the AC outlet or use a fancy 15VDC 3A aftermarket supply. (From: Rudolfs Putnins)
You can power the K19 from the AC outlet or use a fancy 15VDC 3A aftermarket supply. (From: Rudolfs Putnins)

Speaking of DSP, there’s well… a truckload of it. The 31 PEQ bands are more than found in any device on the market right now. They can be controlled via the mobile app or a dedicated desktop program through an RS-232 USB connection. The desktop app is far more intuitive.

Once everything has been set up, most users will use the K19 by leaving most of it to the handy IR remote. It’s a pity that the screen is so tiny because using the K19 at living room distances will mean that you’ll be gouging the config by ear most of the time.

Under the Hood

At the heart of the FiiO K19 is a duo of Sabre ES9039S Pro chips, each of which produces 8 audio channels, which are then summed into balanced stereo to improve the signal-to-noise ratio. The IV stage uses OPA1612 chips, and the analog low-pass filter uses OPA2211. Preamplification is done by OPA1602 pairs.

The K19 has an unusually high number of local regulation for all critical analog stages. (From: FiiO)
The K19 has an unusually high number of local regulation for all critical analog stages. (From: FiiO)

THX AAA 788+ daughter boards amplify the headphone signal, offering 8W into 32 ohms and a whopping 1.1W into 300 ohms. With balanced drive, the K19 has more voltage on tap than the beast-with-80-opamps SMSL SH-X!

The real star of the show here is what happens before the DAC. FiiO K19 employs an Analog Devices ADSP-21565 DSP chip. It’s the first time I’ve seen a company other than RME use a dedicated DSP processor for PEQ. Usually, simple EQ duties are done by the processing muscle that’s found in modern Bluetooth and USB receiver chips.

The FPGA processor only controls the K19, actual DSP calculations are done by a dedicated processor. (From: FiiO)
The FPGA processor only controls the K19, actual DSP calculations are done by a dedicated processor. (From: FiiO)
The QCC5125 Bluetooth receiver can do 212 million instructions per second, and XMOS XU314 tops out at 660 million, while the ADSP-21565 steamrolls them with a whopping 6.4 billion instructions per second!

FiiO has also given extra attention to the power supply section as every critical part of the circuit has dedicated local voltage regulation. Power-nervosa sufferers can forego the built-in switched mode PSU and hook up their own +15VDC linear juice box. Just make sure it can do more than 3A!

Or bring a 15V lithium pack to really dunk on your porta-fi buddies!

Even the 15VDC input is highly regulated in many stages, making fancy power supplies a dubious choice as noise floor will be dictated by the local regulation. (From: FiiO)
Even the 15VDC input is highly regulated in many stages, making fancy power supplies a dubious choice as noise floor will be dictated by the local regulation. (From: FiiO)

How Does the FiiO K19 Sound?

I tested the FiiO K19 using my SMSL SH-X/SU-X combo, Schiit Jotunheim 2, Sennheiser HD6XX, Simgot EA1000, Thieaudio Monarch MK3, Linsoul x HBB Jupiter and Moondrop Para headphones. Imaging capabilities were tested with FiiO SP3 speakers. All tests were done using AC power.

The basic sound signature of the FiiO K19 shows a competent implementation of the ES9039 chip. There’s a certain vividness that’s present in all of the newer ESS DAC implementations I’ve heard recently. For lack of a better word, they all sound more hi-fi than natural. But never clinical, as was sometimes the case with older ESS chips.

The headphone outputs are the standard 4.4mm, 6.35mm and XLR trio. (From: Rudolfs Putnins)
The headphone outputs are the standard 4.4mm, 6.35mm and XLR trio. (From: Rudolfs Putnins)

In terms of technicalities, the K19 delivers. Both micro and macro details are in line with my expectations. Hooking up speakers puts the terrific imaging capabilities on display. This might be the first DSP-capable DAC/amp I’d recommend based on raw analog capability alone.

The THX AAA 788+ headphone amp stage is competent enough to drive just about any headphones. Peak power is achieved in 32-ohm loads. Even the 8-ohm Moondrop Para didn’t feel like it lacked any power. Switching to low-gain leaves plenty of volume control headroom with sensitive IEMs and unwanted noise is never an issue.

On the side we have ventilation inlets and bolt holes for the feet. (From: Rudolfs Putnins)
On the side we have ventilation inlets and bolt holes for the feet. (From: Rudolfs Putnins)

Connecting dedicated amplifiers to the FiiO K19 offers a sound upgrade. After all, the same amplifier circuit is used in USD $200 DAC/amps like the FiiO K7. I’d recommend pairing the K19 with discrete class-A or tube amplifiers to diversify system capability. The THX AAA circuit is known to sound a bit bland at times.

Comparisons

Due to its considerable DSP muscle, the FiiO K19 has little direct competition. FiiO was probably going after the RME ADI-2 DAC, which offers a similar feature set. I used to own its predecessor, the ADI-2 Pro AE, and from memory, it was a bit less impressive in terms of sound but was way more feature-rich.

Despite not using a standard equipment rack size it was easy to buddy up the K19 to the SMSL SH-X. (From: Rudolfs Putnins)
Despite not using a standard equipment rack size it was easy to buddy up the K19 to the SMSL SH-X. (From: Rudolfs Putnins)

The SMSL SU-X is a dedicated double ES9039 chip affair with opamp outputs. During fast AB switching, I can detect that it offers a hair more technical detail, but you need to bring your own amp and DSP to match the K19. If you need only a capable DAC, save the money and go for the SU-X.

Both of the knobs have LED illumination but it changes upon switching sample rate, so chances are you'll only see one color. (From: Rudolfs Putnins)
Both of the knobs have LED illumination but it changes upon switching sample rate, so chances are you’ll only see one color. (From: Rudolfs Putnins)

DSP junkies will be pleased that FiiO’s Q15 and KA17 (review coming) both offer 10 PEQ bands and a very competent performance for their respective price points. In terms of raw performance, only the Q15 can touch the K19, but its AKM chipset offers a markedly different sound flavor.

Software

Controlling the vast DSP capabilities of the K19 can be done in two ways. There’s the FiiO Control app (Apple, Android) for smartphones and tablets and a new FiiO Audio DSP app for Windows. Using the smartphone app is a bit clunky.

The DSP control software on Windows makes setting up a breeze. (From: Rudolfs Putnins)
The DSP control software on Windows makes setting up a breeze. (From: Rudolfs Putnins)

The FiiO Audio DSP program is way more robust as it uses the RS232 port to communicate directly with the DSP chip. It’s far from perfect but a 10 PEQ setup can be made quite easily. You can also store configs as proprietary files and, once loaded, assign them to one of ten custom DSP presets.

I really hope FiiO adds support for EQ config files from squig.link someday.

Overall, I’d call the current software package a usable starting point as there’s a lot that can be improved. For one – being able to assign PEQ bands to specific channels is a must if any kind of speaker or room correction is applied. 31 PEQ bands for headphones are overkill. A more robust mixer for I/O would also help.

The DSP control panel allows for enabling a limiter, dynamic range compressor, and an expander. These feel a bit extra for most listener use cases.

Where to Buy

Who Should Buy This?

Anyone who likes EQing headphones will be in heaven with the FiiO K19 as its vast DSP capabilities can’t be currently matched by any audiophile hardware. The sound quality without using DSP is more than adequate for the price unless a certain coloration is preferred.

Final Thoughts

What’s the reasoning behind putting DSP in a separate box, if we have Equalizer APO or Sonarworks SoundID Reference? There are many, including that some EQ apps can burden your CPU or introduce signal latency. The K19 also adds a handy way to switch profiles with just a click of the remote.

Flat, bassy, gaming profile, or just compare two different corrections – the K19 allows that and more!

Don’t believe in EQ? The K19 is still FiiO’s best effort to date at delivering high-quality sound. It’s not just a K9 Pro with DSP tacked on. The physical package is very sleek and fresh, and the circuit inside is different. Relative to other parts, the headphone amp could’ve been more sophisticated, but it’s better than most all-in-ones.

The K19 needs some software UX fixes to make it easier to use. FiiO has a good track record of delivering firmware updates, so I’m sure fixes and even upgrades are coming. In terms of raw performance, the K19 is the perfect start to an audio endgame.

What’s in the Box?

  • K19 DAC/amp
  • Quick start guide
  • Warranty card
  • AC power cord
  • Type-C to USB-A adaptor
  • Stand brackets
  • Plastic headphone stand mount
  • Philips screw-driver
  • Metal cover for the front XLR
  • Stick-on rubber feet
  • Bolts for the stand legs
  • USB-A to USB-C cable
  • USB-C to USB-C cable
  • 3.5mm TS trigger cable
  • IR remote

Technical Specifications

  • Form: Desktop DAC/Amp
  • Output Impedance (Ohm): <0.6 Ohm SE and BAL
  • Frequency Response (Hz): 20 Hz – 80 kHz
  • THD+N: <0.0003%(1kHz/-6dB @ 32Ω)
  • SNR: >128dB(A) line-out, >128dB(A) headphone out
  • Output power: SE: 4000mW (16Ω, THD+1%), 2300mW (32Ω, THD+N<1%), 270mW (300Ω,THD+N<1%), BAL: 4000mW (16Ω,THD+N<1%), 8000mW (32Ω,THD+N<1%), 1100mW (300Ω,THD+N<1%)
  • Data rates (USB): PCM – 32bit (44.1 – 768kHz), DSD512
  • Data rates (Coax): PCM – 24bit (44.1 – 192kHz), DSD64, output: PCM – 24bit (44.1 – 192kHz)
  • Data rates (Optical): PCM – 24bit (44.1 – 96kHz), output: PCM – 24bit (44.1 – 192kHz)
  • Data rates (HDMI): PCM – 24bit (44.1 – 192kHz) input and output, HDMI ARC (44.1/48kHz)
  • Bluetooth Version: 5.1
  • Bluetooth Audio Codec: AAC, SBC, aptX, aptX LL, aptX Adaptive, aptX HD, and LDAC
  • EQ: 31-band parametric EQ
  • DSP: limiter, dynamic range compressor, and expander
  • Trigger: 12V 3.5mm TS in and out
  • Weight (g): 1800g
  • Size: 250x225x36.7mm

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