FiiO K9
The FiiO K9 delivers a silent, neutral-leaning presentation with crisp resolution, controlled drive and enough authority for most headphones. Soundnews highlights its superb noise floor and strong resolution, while PortaFi finds lively dynamics, realistic detail and versatile connectivity. Stable Bluetooth and serious desktop flexibility make it a high-value all-in-one.
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Deliciously Crispy
Sound Quality
92/100
Build Quality
91/100
Features Usability
91/100
Value for Money
94/100
Pros
Exceptionally quiet background with excellent measured noise-floor performance.
Neutral, controlled sound combines strong resolution with a subtly lively, engaging dynamic character.
Versatile DAC/amp functionality, plentiful connections, and stable low-latency Bluetooth broaden desktop and multimedia appeal.
Compelling value versus the K9 Pro ESS, retaining substantial technical capability at a lower price.
Cons
Lacks MQA support and the side-mounted USB-C OTG port available on the K9 Pro ESS.
Power output is lower than the K9 Pro, so performance with the most demanding headphone loads is less certain.
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What Reviewers Are Saying
SOUND QUALITY PERFORMANCE 92/100
Reviewers describe a clean, neutral-leaning and technically capable presentation with strong detail retrieval, controlled power and an engaging touch of drive. Its background is reported to be exceptionally quiet, while available listening comments indicate ample authority for most headphones.
Transparency Resolution
93/100
Soundnews rates resolution at 93/100, and PortaFi hears convincing fine detail that makes acoustic instruments sound more realistic. PortaFi also finds treble extension clearly above average, with both fundamental tones and richer overtones reproduced well.
Tonal Balance Musicality
91/100
PortaFi characterizes the K9 as largely neutral and controlled rather than overtly colored. It adds a small amount of typically FiiO-like dynamic emphasis, giving the presentation a slightly more emotional and lively character without moving far from neutrality.
Dynamics
89/100
Soundnews scores dynamics at 89/100. PortaFi reports good control, useful power reserve for most headphones, and a mildly enhanced sense of drive, though the available comments stop short of calling it an outright powerhouse.
Noise Floor
95/100
Soundnews awards the K9 a 95/100 noise-floor result, indicating a notably silent background. No supplied review reports hiss, hum, or other background-noise concerns.
Headphone Compatibility
90/100
PortaFi finds sufficient power in reserve for most headphones and describes the amplifier as controlled in use. The supplied reviews provide limited specific pairing evidence with very sensitive IEMs or unusually demanding planar headphones, so its performance at those extremes is less fully documented.
Assessments of Build Quality, Usability, and Overall Propositions.
Build Quality
91/100
Soundnews rates build quality at 91/100. PortaFi describes a substantial metal chassis and the familiar robust FiiO design, while Audiophilepure notes only a small weight reduction relative to the K9 Pro ESS.
Features Usability
91/100
The K9 combines DAC and headphone-amplifier duties, offers numerous inputs and outputs, and can also serve as a DAC or feed an external amplifier. PortaFi reports stable Bluetooth performance through a wall and low enough latency for video and gaming; the main omissions noted are MQA support and the side USB-C OTG port found on the K9 Pro ESS.
Value for Money
94/100
At $500, Audiophilepure calls the K9 a compelling alternative to the K9 Pro ESS and a pleasant surprise given its technical capability. Soundnews gives value 94/100, while PortaFi calls it a highly successful way to save money without giving up much sound quality.
Reviews & Sources
Professional reviews and sources for this product's Watt'n Potatoes analysis.
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Specifications
Manufacturer's Description — FiiO
High performance ES9068AS*2 DAC | THX AAA 788+ amplifier
Dual-mode clock management | QCC5124 Bluetooth
LDAC/aptX Adaptive and other high-res Bluetooth format support
App connectivity | Truly balanced design
Dual-voltage linear transformer | Variety of inputs and outputs
* Pictures are for reference only. The actual product may vary.
Note: The product layout is for reference only. All products shall prevail.
Selling Points
High-performance dual cores for soul- shaking sound
Two ES9068AS DACs handle the left and right channels, and make up the high-quality "core" of the K9. Listen to your favorite playlist and be instantly immersed in the music.
High-end amplifier Refreshingly capable
The FiiO K9's ace up its sleeve is the THX AAA 788+ amplifier, giving it an extraordinary 1% undistorted power output up to 780mW at 300Ω and up to 2000mW at 32Ω. No matter if you use low-impedance or high-impedance headphones, the K9 will drive it with aplomb.
Precisely designed
Fully balanced design music to your ears
From the DAC, to the volume adjustment, to the amplification, every part of the K9 is truly balanced for greatly reduced crosstalk and more authentic sound.
Partitioned design for max performance of each section
The PCB of the K9 features a partitioned layout, fully separating the major sections of the audio circuit – the power supply, signals, and analog signal loop. This guarantees the integrity of the audio signal being processed.
Six-stage audio circuit faithfully reproducing sound
The desktop-grade six-stage audio circuit was meticulously designed to ensure a pure, delicate yet rich sound. I/V conversion, LPF filter, digital volume adjustment, buffer amplifier, pre-amplifier, post-stage drive
Electricity is the mother of sound
Robust power supply, ample power
The linear transformer is paired with 4 massive 4700uF capacitors to provide clean continuous power.
Isolated digital and analog section power supply, for purer sound
The digital and analog portions of the K9 receive power separately to reduce interference between the two audio circuits, for pure and faithful reproduction of your music.
Multiple LDOs in multiple stages, truly stable power
The power stabilization and filtering within the audio circuit plays a big part in ensuring excellent sound quality. Each stage of the audio circuit employs ultra-low-noise LDOs for voltage regulation.
Dual-mode clock management, even more improvement to sound
Accurate and stable dual-mode clock management allows the K9 to easily play back high-resolution audio with the greatest fidelity, as if you were there with the performing artists.
* Supports up to 768kHz/32bit PCM and DSD512
High-res Bluetooth Adept at all of your audiovisual needs
The K9 employs the QCC5124 Bluetooth chip with support for LDAC/aptX HD/aptX Adaptive and other high-res Bluetooth formats. With the K9, you can listen to music, watch videos, and play video games with high quality and low latency.
*Bluetooth 5.1, supported formats: LDAC/aptX Adaptive/aptX/aptX HD aptX LL/AAC/SBC
Compatible with UAC 1.0/UAC2.0, highly adaptable
The K9 supports both UAC1.0 and UAC2.0 modes, allowing you to use the K9 with either devices that are simply plug-and-play or with devices that can work with the K9 with an additional driver for even better compatibility. And the FiiO Control App allows you to easily switch between UAC1.0 and UAC2.0 modes.
*UAC1.0 for PS5 and other device support
Comprehensively capable No matter where you look
Inputs: USB, optical, coaxial, RCA, 4.4mm
Outputs: 6.35mm SE, 4.4mm balanced, XLR-4 balanced
Five input signals: USB input/optical/coaxial LINE/Bluetooth
*LINE mode includes RCA and 4.4mm input. If both are connected, the 4.4mm input is prioritized.
LO:
Only the rear RCA+XLR analog outputs are active, at max output and cannot be adjusted by the volume knob;
PRE:
Only the rear RCA+XLR analog outputs are active, and can be adjusted by the volume knob;
PO:
Only the front headphone outputs are active, and can be adjusted by the volume knob
file L:
L level for low gain is designed to better pair with sensitive in-ear earphones;
H file:
H level for high gain is designed to better drive lower sensitivity over-ear headphones.
Neatly handsome Horizontal or vertical
The K9 adopts the well-received design language of other FiiO desktop units, and features an all-aluminum construction made from an integrated stretching + CNC process to ensure the body's strength and precise finish. And with the vertical stand, the K9 can be used either vertically or horizontally, allowing it to become a versatile part of your desktop setup.
A weighty feel For a weighty sound
The iconic, weighty FiiO volume knob is powered by ADC curve reconstruction to allow you to precisely and smoothly adjust through 120 levels of volume, with minimal noise and volume deviation between the left and right channels.
Light it up Let the high-res music commence
Not only do the RGB lights around the knobs give the K9 and the desk space around it some fun personality, they also conveniently indicate the current audio sampling rate and Bluetooth format.
Professional PEQ For what you love
Through the FiiO Control app, you can quickly switch between 7 music tuning styles preset on the K9. If the selected tuning style fits the music you are listening to, you can acquire a more vivid and pleasant experience. If the preset tuning style is not to your liking, the 3 self-define PEQ (Parametric Equalizer) designs will help to fine adjust to your favorite listening style.
*This function is only valid for Bluetooth decoding.
To show off your skills
One app is enough
You can connect the K9 to your phone via Bluetooth, and with the addition of the FiiO Control app you get access to even more functionality. Adjust various settings such as filters, status indicators, EQ, and channel balance to exactly your liking.
*EQ only works in Bluetooth mode.
Multiple intelligent protection systems Always ready to go
Three intelligent protection systems – preventing overheating, overload, and DC protection – constantly make sure that the K9 delivers high-energy music without wearing itself out. Listen worry-free with the K9!
Immerse yourself in fabulous music
Connect via USB cable to a desktop or notebook computer
Connect to a phone via USB-B to Type-C cable
Connect to a phone, tablet, etc. via Bluetooth
Connect to a desktop digital player
Connect to external amplifiers or active speakers
Comparison table of the K series products
Abundant accessories
K9*1, Power cord*1, Headphone plug adapter*1, USB data cable*1, Feet pads*6, Fuse*1, Stand*1, Quick start guide*1, Voltage selection card*1, Warranty card*1
Verified Dealers
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Authorized dealers for FiiO K9
- 110Hz — online and in-store — Kielce, Województwo świętokrzyskie, Poland (website)
- Acoustic Technologies — online and in-store — Montréal, Québec, Canada (website)
- Addicted to Audio — online and in-store — Epping, Victoria, Australia (website)
- Advanced MP3 Players — online and in-store — Musselburgh, Scotland, United Kingdom (website)
- All Elite Audio — online and in-store — Perry Hall, Maryland, United States (website)
- Alpha Audio Pte — online and in-store — Singapore, Singapore (website)
- Apos Audio — online and in-store — Oakland, California, United States (website)
- Audeos — online and in-store — Żywiec, Województwo śląskie (website)
- Audio 46 — online and in-store — New York, New York, United States (website)
- Audio Affair — online and in-store — Deritend, England, United Kingdom (website)
and 59 more verified dealers