90%
FiiO K9 Pro
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.
Dealers selling FiiO near you
FiiO K9 Pro — a quiet, resolving three-in-one
The FiiO K9 Pro combines a dual ES9038PRO DAC implementation with a powerful THX AAA-788 headphone stage to deliver a very low noise floor (≈129 dB SNR), detailed, and neutral sound that foregrounds timbre and micro-detail. According to Steven Stone of Future Audiophile, it preserves subtle background information and places instruments cleanly in the soundstage. Connectivity is comprehensive (USB, coax, optical, Bluetooth with modern codecs, MQA and DSD support) and the companion FiiO Control app adds EQ, balance and remote volume control. Build quality is solid, with a linear PSU and a preamp output capable of high voltage, though the unit runs moderately warm. The K9 Pro suits listeners who want a single-box DAC/preamp/amp with pro-level specs and excellent value for its performance class.
Pros
- Exceptional noise floor and resolution enabled by dual ES9038PRO DACs, producing an effectively silent background for sensitive headphones and speakers.
- Powerful and versatile headphone amplification (THX AAA-788), shown to drive both hard-to-drive cans and efficient models with authority.
- Neutral, highly resolving presentation with strong instrument separation and imaging that keeps the music transparent rather than colored.
- Feature-rich connectivity and control — USB/coax/optical, wide Bluetooth codec support, MQA/DSD decoding and a full-featured companion app with EQ and balance.
&
Cons
- Unit runs moderately warm in normal operation, a consequence of its linear PSU and dense internal electronics.
- User interface quirks — the multicolor ring that indicates sample/bitrate is not intuitive and the large volume knob lacks clear markings for repeatable reference levels.
- No dedicated physical remote included, making some users reliant on the smartphone app for remote control.
Sound Quality
90/100
The review highlights excellent retrieval of low-level background bits and natural instrument separation, implying strong micro- and macro-dynamics. The THX AAA-788 headphone stage and high power capability support confident transient and dynamic performance with demanding material and headphones.
Noise Floor
92/100
The reviewer cites a 'staggering 129 dB signal-to-noise' and says the K9 Pro can deliver an 'effectively silent background noise level even with the most sensitive speakers or headphones.' That explicit praise supports a very high noise-floor rating suitable for sensitive IEMs.
Headphone Compatibility
90/100
The built-in THX AAA-788 amp is rated at 1100 mW into 300 ohms and the preamp section offers up to 52 V peak, and the reviewer notes it can drive both Dan Clark Stealth and a 600 Ω DT 990. Those specs and real-world examples indicate broad compatibility from efficient IEMs to hard-to-drive planars; output impedance and gain-step specifics were not provided, so a small caution is retained.
Build Quality
86/100
Construction appears solid with a linear power supply and dual DACs, but the reviewer notes the unit 'does get moderately warm when running' due to its internal design. No mechanical or finish issues are raised, but the thermal behavior is a minor drawback.
Features Connectivity
88/100
The unit includes a high-quality ESS-based dual-DAC implementation and a powerful THX AAA-788 headphone stage, plus a preamplifier output capable of 52 V peak — all called out by the reviewer. The review does not list balanced outputs, specific digital inputs, or streaming features, so feature additions were scored conservatively while recognizing the strong built-in DAC and preamp functionality.
Value for Money
89/100
At the reviewed price point (~$849 mentioned), the reviewer explicitly states the K9 Pro 'delivers more value per dollar' than a Topping D90 SE and positions it as a strong option for audiophiles building higher-end systems. That positive comparative language justifies a solid value score.
Reviews
Online Reviews & Mentions
YouTube Reviews
Forum Mentions
No forum mentions found yet
FAST, EASY & NEAR
Find FiiO Verified Dealers Near You
FiiO dealers in the map