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.

K9 Pro

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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.

Electricity is the mother of sound

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.

Isolated digital and analog power delivery

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!

LDOs for each audio circuit stage

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 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.

Listen to true beauty

THX AAA amplifier technology

*As tested in FiiO Labs under balanced out

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.

The strength to always triumph Legendary AK4499

Precise Design for Highly Demanding Needs


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.

· Fully differential, truly balanced design

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.

Clearly partitioned for smooth signal transmission


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

Six-stage audio circuit that holds up to scrutiny


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.


Dual femtosecond clocks of excellence


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.

Lossless MQA decoding


*Supports up to MQA 8x decoding with applicable music apps.

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


Fast and reliable

hi-res Bluetooth


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.

Essentiality of volume adjustment

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.



Headphones come alive with a good source


Drive power-hungry headphones (desktop USB audio + headphones)

A true Renaissance man

 Connect to home audio setup (desktop USB audio + active HiFi speakers)

Side-mounted Type-C port for easy connection to mobile devices

RCA+XLR balanced line out (for active speakers, monitor speakers, external amplifiers)

*When connected via Line out, you can quickly switch   between fixed and variable output.

Connect to mobile devices (players, computers)

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.



App-controllable desktop amp


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.

Perfection exemplified

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.



Lighting up the mood


Rich sound from plentiful connectors



6.35mm single-ended

4.4mm balanced

XLR balanced output




USB Type-C port

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.



Switch quickly to your music