FiiO K9: Close to perfect

FiiO K9 Review
FiiO K9 Review

The Chinese audio company specializing in portable audio products has garnered a significant following over its 16-year history. Initially focusing on headphones, the company has since expanded its product range to include stationary jacks and speaker systems. Today, I will be reviewing the FiiO K9, a stationary DAC and amplifier that serves as a simplified version of the K9 PRO. The K9 PRO originally utilized the AK4499EQ chip, but due to production issues following a fire in 2020, FiiO had to transition to the ES9038 PRO chip. Despite this change, the K9 still offers impressive capabilities and high resolution, surpassing even its PRO counterpart.


Let’s begin by discussing the packaging and setup of this DAC. Upon first glance, the box appears to be a simple black color, featuring a blue textured outline of the device. However, when exposed to bright light, it exhibits a mesmerizing iridescent effect, truly captivating the eye. Additionally, the FiiO logo, as well as the HiRes Audio and HiRes Audio Wireless emblems, are prominently displayed on the box.

Upon opening the box, you will find the user’s manual placed on top, along with a vibrant orange brochure that bears the cautionary label “WARNING”. It is worth noting that there is a voltage switch located at the bottom of the device, offering two positions: 115 and 230 volts. It is crucial to ensure that you have it set to 230 volts, as this aligns with the voltage used in our networks.

Moving further into the box, you will discover the FiiO K9 itself. To ensure its utmost protection and stability during transportation, it is thoughtfully lined with foam. Additionally, a separate box containing various accessories accompanies the DAC.

Inside the box:

  • power cable
  • stand for vertical placement
  • cable USB B – USB A (for connecting to a sound source)
  • fuse
  • 6 silicone legs
  • plug for voltage switch (bottom)
  • adapter for 6.3 mm
  • warranty card

The device has a simple, understated, yet elegant appearance. Made of black aluminum, it is quite heavy at around 2660 grams. It easily attracts fingerprints, but they can be easily wiped off. The device features a classic rectangular shape with a small depression in the center, likely intended for full-sized headphones. Ventilation holes on the sides help with heat dissipation. While in use, the FiiO K9 warms up slightly, reaching temperatures of 37-40 degrees. In comparison to the K9 PRO, it does not have the gold-colored design elements, and in terms of size and weight, they are nearly identical.


FiiO K9  come quipped with:

  • with two ES9068AS chips
  • XMOS XUF 208 decoding chip
  • double THX AAA 788+ amplifier
  • bluetooth chip QCC5124, Bluetooth 5.1

Audio formats: PCM up to 768 kHz, DSD512

Bluetooth formats: LDAC, aptX, aptX Adaptive, aptX HD, aptX LL, AAC, SBC

Output interfaces:

  • 6.3 mm, 4.4 mm, XLR-4, RCA, XLR

Input interfaces:

  • USB, OPT, COAX, RCA, 4.4 mm

Output power:

  • 1 L+R 2000 mW+2000 mW (32 Ohm balanced)
  • 2 L+R 780mW+780mW (300 Ohm balanced)

Weight: approximately 2660 grams

Dimensions: 200×224.5×72 mm

Connection interfaces and controls

From the front, the XLR-4 plug is visible, along with the 6.3mm (PO) and 4.4mm (BAL) connectors for headphone outputs. Positioned to the left is the branded volume control wheel, featuring 120 positions from initial to final. A circular RGB backlight surrounds the controller, providing both aesthetic appeal and indicating the quality of the material being played, whether through a wired connection or Bluetooth.

Located at the top right is an LED indicator displaying the selected connection interface (USB, optical, coaxial, line, Bluetooth). At the bottom right, two switches are present: the first one adjusts the volume control (bottom position (PO) – headphone output from the front panel with adjustable volume, middle position (PRE) – line output on the rear panel with adjustable volume, top position (LO) – line output to the rear panel with fixed volume controlled solely by the sound source). The second switch alters the gain of the amplifier, offering options for low, medium, or high gain.

On the right side, there is a button for selecting the connection interface. In the lower right corner, a multifunctional button serves to mute the sound and enter standby mode with a single press, while holding it for 5 seconds powers off the device. Moving to the back, the power switch and power connector are visible. Additionally, there is a Bluetooth antenna on the right side. Inputs include coaxial, USB (for connecting phones, tablets, laptops, or computers), optical input, a 4.4mm balanced input for external players, and RCA inputs. Outputs for speaker systems consist of unbalanced RCA and balanced XLR connections. Notably, the absence of a type-C input for smartphones distinguishes it from the K9 PRO.


I discussed the interfaces and controls earlier, but before diving into the most intriguing aspects, let me share how I utilized them, along with the features of the application. I connected the K9 to my laptop, using my audio library, and also linked it to my phone through an iFi OTG adapter. To fully utilize its capabilities, you need to install the FiiO Control Panel program on your Windows or Mac. The volume wheel’s illumination changes based on the input signal type and sample rate. FiiO’s official website provides an image that explains the color scheme. Interestingly, when switching Bluetooth codecs, the backlight color also changes.

My Android smartphone supports aptX, so it seamlessly adapted to the K9. Connecting and adjusting sound via Bluetooth is done through the FiiO Control application on the smartphone. Additionally, it’s worth mentioning that the K9 PRO differs from its predecessor by supporting higher sampling rates: up to 768 kHz instead of 386 kHz for PCM and DSD512 instead of DSD256. Now, let’s briefly explore the application interface.

Once your smartphone is connected to the DAC and you select K9 on the main screen, you’ll see a status screen displaying your device’s image, name, codec, and sample rate. Below, there’s a switch for UAC 1.0 to enhance compatibility with older devices. Moving on, you can customize the display, choose Bluetooth codecs, and select the audio source (USB, optical, coaxial, line, or Bluetooth) at the bottom. On the second tab, you can fine-tune the 10-band EQ from 32 Hz to 16 kHz and add up to 12 dB of gain.

You can disable the equalizer or choose from pre-configured options. The button on the right allows for more precise adjustment of each equalizer column, known as the wave equalizer without fixed values. The third tab enables you to adjust the balance between the left and right channels and apply a low-pass filter with various decay rates.


Now let’s move on to the most captivating aspect of this review: the sound. I had the opportunity to listen to them using both the full-size Meze 109 Pro headphones and the FiiO FD5 vacuum-type headphones, comparing them with the Shanling H5.

Starting with the presentation and character of the DAC itself, as mentioned earlier, it has an analytical nature with a focus on microcontrast. This characteristic is noticeable when paired with headphones of a similar class and price range. It’s important to consider specific connections and headphone setups when choosing the sound that suits you best.

When using the Meze 109 Pro headphones, which are known for their audiophile quality and genre versatility, the sound is highly analytical with an emphasis on microcontrast. This means that every detail is meticulously reproduced, allowing you to fully immerse yourself in genres such as jazz, blues, and classical music. The delivery is mature and warm, providing a truly enjoyable listening experience. Additionally, the Meze 109 Pro headphones excel in creating a captivating soundstage that brings your music to life.

In terms of frequencies, the low frequencies are pleasant, soft, and warm, without being overly emphasized. The bass is well-defined with varying depths, although it may not reach the deepest levels and may not be suitable for all genres. Moving on to the middle frequencies, they are extended and airy, thanks to the open design and 50 mm dynamics of the headphones. The overall presentation is complete, with warm and pleasant vocals that envelop your ears like honey, creating a cozy and soothing sound.

As for the high frequencies, they are slightly accentuated and analytical, allowing you to hear every detail of the recording. When listening to familiar tracks, you may notice nuances and moments that went unnoticed before, giving a fresh perspective to old favorites. The microcontrast is particularly impressive, adding another layer of depth to the sound.

Overall, the sound quality provided by the Meze 109 Pro headphones, in combination with this DAC, is truly remarkable. It offers a detailed and immersive listening experience, particularly suited for those who appreciate analytical sound reproduction and a focus on microcontrast.

The sound of the FiiO FD5 is truly remarkable, especially when both the headphones and DAC are from the same brand. The FD5, being a serious dynamic model with a 12 mm driver made of diamond-like carbon coated with beryllium, offers a unique listening experience. As the brand’s flagship dynamic headphones when I purchased them, I was immediately drawn to the way they handle low frequencies – with a slight accentuation that brings out the nuances and layers in the bass. This is a stark contrast to cheaper headphones that tend to flatten out such differences. Additionally, the middle frequencies are beautifully presented with a natural tone that allows for clean transmission of male and female voices without any distortion, while maintaining high levels of detail. The soundstage in these headphones is surprisingly good given their form factor, leaving you in awe of their capabilities. Furthermore, the high frequencies are extended, well-defined, and accentuated, with fast and precise attacks.

When comparing the FiiO K9 to the Shanling H5, it becomes evident that the microcontrast is slightly diminished in the Meze, while the depth is enhanced, maintaining the headphones’ genre specificity. On the other hand, the FD5 offers a more enjoyable and versatile sound experience, with accentuated bass that caters well to various music genres. While the Meze may not be suitable for all music styles due to its genre-specific presentation, the FD5’s bass emphasis allows for a more engaging listening experience, especially for genres like electronic music where bass plays a crucial role. Switching to the K9 reveals a more detailed sound profile, with textured and well-developed bass, showcasing the importance of comparison in understanding the nuances of audio quality.


FiiO has successfully created an intriguing stationary device at a more affordable price point, surpassing its older counterpart in certain aspects. Despite lacking a type-c connector, one can easily purchase an OTG cable to resolve this inconvenience. With its impressive sample rate and the added benefit of detailed sound, accentuated microcontrast, and analytical capabilities, this DAC/amplifier is highly recommended for home music listening. Moreover, it offers versatility by allowing users to connect it to their phone, tablet, laptop, computer, speaker system, or even a hi-fi player through the 4.4 mm connector. What more could one ask for?

FiiO K9 Review
FiiO K9
Qln Reference 9

QLN unveils floorstanding Reference 9 seakers at Axpona


KZ ZS10 PRO2: Hybrid headphones with 4 sound adjustment switches