FiiO K9 Pro
The FiiO K9 Pro pairs a silent background with lucid detail, spacious imaging and enough power for demanding headphones. Future Audiophile found its timbral balance unusually accomplished, while Joshua Valour praised its smoother, more open take on THX precision. Extensive digital, analogue and balanced connectivity makes this a seriously capable desktop hub.
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Deliciously Crispy
Sound Quality
93/100
Build Quality
92/100
Features Usability
94/100
Value for Money
92/100
Pros
Highly resolved, clean and spacious sound with precise instrument placement and strong retrieval of low-level detail.
Very quiet performance, including with sensitive headphones and IEMs at appropriate gain settings.
Powerful, versatile all-in-one with balanced and single-ended headphone outputs, extensive inputs, preamp functionality and app control.
Dense, premium-feeling construction and strong value relative to separate DAC, preamp and headphone-amplifier solutions.
Cons
Runs moderately warm in use, so ventilation and placement deserve consideration.
Colour-coded format indication is not especially intuitive, and the unit lacks a dedicated physical remote.
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What Reviewers Are Saying
SOUND QUALITY PERFORMANCE 93/100
Reviewers consistently describe a clean, highly detailed and spacious presentation, with strong control and a notably quiet background. Its sound is fundamentally neutral and precise, but several listeners also hear a welcome touch of warmth, weight and smoothness that keeps it from sounding sterile.
Transparency Resolution
94/100
Future Audiophile praises the K9 Pro's subtle-detail retrieval, lack of haze and ability to separate instruments effortlessly. Audiophile Heaven calls it exceptionally clear, vivid and detailed, while PortaFi finds good resolution and texture even if it does not spotlight micro-contrast as aggressively as a dedicated monitoring component.
Tonal Balance Musicality
91/100
The overall balance is described as neutral, coherent and uncoloured, with extended treble that is neither pushed nor recessed. Joshua Valour heard a slightly warmer, smoother and more forgiving presentation than many THX designs, while PortaFi notes a little added weight and forward vocal presence.
Dynamics
92/100
Reviewers report impactful, controlled bass, quick transient response and convincing macro-dynamic drive. Joshua Valour highlights strong imaging, dynamics and bass authority, while PortaFi attributes improved dynamics and naturalness to the more powerful amplification.
Noise Floor
94/100
Future Audiophile found the background effectively silent even with very sensitive headphones, supported by the unit's extremely strong signal-to-noise performance. PortaFi likewise reports surprisingly low noise on low gain with IEMs, and no reviewer identifies audible hiss or hum as a practical issue.
Headphone Compatibility
93/100
The K9 Pro is repeatedly described as powerful and capable with demanding headphones, including the Dan Clark Stealth and 600-ohm Beyerdynamic DT 990. Z Reviews says it powers every headphone, while low-gain operation also appears well suited to IEM use.
Assessments of Build Quality, Usability, and Overall Propositions.
Build Quality
92/100
Multiple reviewers praise the dense all-metal construction, smooth volume control and unusually high standard of assembly for the price. The main practical caveat is that the unit runs moderately warm during operation, owing to its internal power supply and processing hardware.
Features Usability
94/100
This is a notably complete desktop DAC/amp, with USB, optical, coaxial, Bluetooth, RCA and balanced 4.4mm inputs alongside RCA and balanced XLR line outputs. It also supports high-resolution PCM, DSD and MQA, offers app control for many functions, and can serve as both a headphone system and preamp.
Value for Money
92/100
At roughly $800–$850, reviewers regard the K9 Pro as a strong-value all-in-one rather than a compromised budget option. Future Audiophile considers its capable headphone section an advantage over the more expensive Topping D90 SE, while Joshua Valour calls it worth its asking price given the sound, build and connectivity.
Reviews & Sources
Professional reviews and sources for this product's Watt'n Potatoes analysis.
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Specifications
Manufacturer's Description — FiiO
K9 Pro
Collector's AK4499 chip | THX AAA 788+ Tech | Dual femtosecond clocks
Qualcomm QCC5124 | Supports LDAC/aptX Adaptive/aptX HD | App control
Truly balanced design | Dual voltage linear transformer | Wide connector selection
*Pictures are for reference only. The real product may vary.
Something you will want to keep
The K9 Pro, conceived as a flagship from the very beginning, is designed to be uncompromising as both an amp and a DAC. Its outstanding performance will ensure you want to leave a spot for the K9 Pro in your collection of audio gear.
The strength to always triumph Legendary AK4499
The K9 Pro is equipped with the legendary AKM AK4499, renowned in the audio industry for its exceptional performance and unparalleled decoding capabilities, supporting up to 384 kHz and native DSD256 audio. And given its current scarcity, it is definitely a chip many are eager to experience.
Listen to true beauty
THX AAA amplifier technology
The THX AAA 788+ module used in the K9 Pro provide exemplary details and dynamics no matter if you are using low or high-impedance headphones. The K9 Pro can output up to 46Vpp transients when driving high-impedance loads, and up to an undistorted 2W* when pushing low-impedance loads. Compared to the original, the output power of the K9 Pro has increased by more than 50% with higher heat dissipation efficiency.
*As tested in FiiO Labs under balanced out
Precise Design for Highly Demanding Needs
Six-stage audio circuit that holds up to scrutiny
· Fully differential, truly balanced design
Every audio signal goes through a mammoth 6-stage circuit to reproduce music as faithfully as possible with every last detail.
I/V conversion, LPF filter, volume control, buffer amplifier, pre-amplification, output-amplification
Fully differential signals go through the four-channel DAC, four-channel volume adjustment, and four-channel amp for a truly balanced design. Such a design ensures minimal interference between different components in order to fully maintain all details and large dynamic swings in music for unmatched sound quality.
Clearly partitioned for smooth signal transmission
The PCB of the K9 Pro uses a partitioned layout, wherein not only the power supply and signals are separated, but the analog signal loop is also put in an independent section, guaranteeing the integrity of the audio signal being processed.
Electricity is the mother of sound
Isolated digital and analog power delivery
LDOs for each audio circuit stage
Linear power supply
The digital portions of the K9 Pro receive power separately from the analog portions, for effective shielding against audio interference between the two circuits. Such a design leads to a highly pure, clean sound.
While the special high-performance transformer is important to the K9 Pro's phenomenal sound, special attention was also paid to the power stabilization and filtering within the audio circuit. In each stage of the audio circuit, ultra-low-noise LDOs are employed for voltage regulation. No expense was spared in ensuring clean power supply, with the K9 Pro in total having a substantial amount of 20 LDOs!
The K9 Pro's linear power supply, with its low-frequency transformer and high-capacity Nichicon capacitors, provides abundant clean power for the whole system.
Dual femtosecond clocks of excellence
The newest generation of XMOS chips supports dual-mode clock management technology. Under USB and Bluetooth decoding dual asynchronous femtosecond clocks are used, while under optical and coaxial decoding automatic PLL clocks are employed. A more precise clock management system makes it easier to handle any kind of source and maintain the maximum quality possible.
Lossless MQA decoding
The K9 Pro supports MQA Renderer, allowing you to listen to high-resolution audio files that are not only reasonably sized, but also retain master-level sound quality that brings you directly into the recording studio.
*Supports up to MQA 8x decoding with applicable music apps.
Fast and reliable
hi-res Bluetooth
The K9 Pro employs the Qualcomm QCC5124 to handle Bluetooth duties, with support for formats such as LDAC, aptX HD and aptX Adaptive. This chip ensures that Bluetooth connections are both reliable and quick, satisfying both the low latency needs for games/videos and the high bitrate necessary for high resolution audio.
Bluetooth format support: AAC/SBC/aptX/aptX LL/aptX HD/LDAC/aptX Adaptive
Essentiality of volume adjustment
Adjusting the volume may look like a simple concept, but a good execution of it is crucial to an excellent audio experience. The ADC curve reconstruction method of volume adjustment used in the K9 Pro effectively minimizes any left-right channel volume imbalance and noise. It also results in a smooth change of volume across all levels. This attention paid to the simple process of volume adjustment is just another layer to making sure you truly savor your music with the K9 Pro.
*Pictures and objects may slightly color difference, please in kind prevail.
Headphones come alive with a good source
Switch between high, medium, and low gain to fit exactly your needs when listening to your particular pair of headphones. Thanks to the pure hardware gain circuit, even when listening at low gain with high-sensitivity headphones both dynamic range and musical fidelity remain uncompromised.
Perfection exemplified
The simple, yet elegant all-aluminum black exterior is anodized and finely sandblasted with painstaking craftsmanship for a textured, luxurious feel. Controls are clearly and intuitively laid out to make operating the device as smooth as possible. Rest assured, the K9 Pro is the very definition of a reliable and loyal music partner in your home.
Lighting up the mood
The stainless-steel volume knob blends seamlessly with the aluminum alloy front panel to give a luxurious experience while controlling your music. The RGB indicator lights surrounding the volume knob can light up differently depending on the currently playing sampling rate.
Switch quickly to your music
Easy-to-use metal switches are used for controlling input selection and gain level to help you easily and quickly switch to your desired method of listening.
Rich sound from plentiful connectors
XLR 4
4.4mm balanced
6.35mm single-ended
Coaxial
XLR balanced output
Optical
RCA
USB Type-C port
A true Renaissance man
Drive power-hungry headphones (desktop USB audio + headphones)
RCA+XLR balanced line out (for active speakers, monitor speakers, external amplifiers)
Connect to mobile devices (players, computers)
Side-mounted Type-C port for easy connection to mobile devices
Connect to home audio setup (desktop USB audio + active HiFi speakers)
*When connected via Line out, you can quickly switch between fixed and variable output.
App-controllable desktop amp
Built-in Bluetooth Low Energy (BLE) technology allows you to use the FiiO Control App to control functions like channel balance, sleep timer, etc. at any time, even when not in Bluetooth mode.
Verified Dealers
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Authorized dealers for FiiO K9 Pro
- 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