Electricity is the mother of sound, so special attention was paid to optimizing the K9 Pro ESS’s power supply to ensure excellent sound. The K9 Pro ESS’s linear power supply, with its low-frequency transformer and 4 massive 4700uF capacitors, makes sure that the rest of the system gets abundant clean power.
Electricity is the mother of sound
Linear power supply
The digital portions of the K9 Pro ESS physically receive power separately from the analog portions, for effective shielding against audio interference between the two circuits. This ensures pure and faithful reproduction of your music.
* Due to the instability of the supply chain, some materials may be replaced due to shortage. The accompanying drawings are for reference only.
Just pure sound,
Isolated digital and analog power delivery
Besides the special high-performance linear power supply, the power stabilization and filtering within the audio circuit is also a big contributor to the K9 Pro ESS’s excellent sound. Specifically, in each stage of the audio circuit, ultra-low-noise LDOs are employed for voltage regulation.
Quality and quantity,
LDOs for each circuit stage
The THX AAA 788+ chips used in the K9 Pro ESS provide exemplary details and dynamics no matter if you are using low or high-impedance headphones. The K9 Pro ESS can produce an undistorted 1100mW* under a 300Ω load, and an undistorted 2100mW* under a 32Ω load, 50% higher than the original THX AAA 788 amplifier chips.
*As tested in FiiO Labs under balanced out.
Pure clean sound,
satisfying even demanding listeners
Inside the K9 Pro ESS are 2 ES9038PRO DAC chips, specifically designed for maximum performance in desktop-grade equipment. One ES9038PRO chip, with all of its 8 parallel outputs, is used for each channel to achieve richly detailed sound with minimal distortion.
Moves your human “core”,
and not just by a little!
Fully differential signals go through the DAC, volume adjustment, and 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, fully balanced design
The PCB of the K9 Pro ESS 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.
Separated analog and digital sections,
Every audio signal goes through a mammoth 6-stage circuit to reproduce music as faithfully and as detailed as possible.
Six-stage audio circuit, to reveal every last detail
A dual-mode clock management design is utilized for the K9 Pro ESS. 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.
The K9 Pro ESS supports the unfolding of MQA tracks, allowing you to listen to high-resolution audio files that are not only reasonably sized, but also retain master-level sound quality that bring you directly into the recording studio.
MQA Renderer, Lossless sound reproduction
*With an appropriate music player supporting MQA, the K9 Pro ESS supports up to 8x unfolding
The K9 Pro ESS 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
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 ESS 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 ESS.
Essentiality of volume adjustment
Choose between high, medium, and low gain with a physical switch 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.
Dial it in with
three gain levels
Drive power-hungry headphones (desktop USB audio + Headphones)
A true Renaissance man
Connect to home audio setup (desktop USB audio + active speakers)
Side-mounted Type-C port for easy connection to mobile devices
RCA+XLR balanced line out (for active speakers, monitor speakers, external amplifiers)
Connect to mobile devices (players, computers)
App-controllable desktop amp
Built-in Bluetooth Low Energy (BLE) technology allows you to use the FiiO Control App to control functions like filter selection, channel balance, etc. even when not in Bluetooth mode.
The RGB indicator lights surrounding the volume knob can light up differently depending on the currently playing sampling rate.
Rear: 4.4mm balanced line in; coaxial, optical, Bluetooth, RCA, USB input; RCA SE out and XLR*2 balanced out
Type C port
Side：USB Type-C port
The included custom stand not only reduces the amount of space the K9 Pro ESS takes on your desktop, it also allows for more efficient dissipation of heat through convection – making the stand a true example of both form and function.