
























FiiO - K9 Pro ESS
Flagship Desktop DAC & Amplifier
Unfortunately, even if we desire to, we won't be able to resurrect this product. The Museum is where we pay our respects to end-of-life, old, archived, but not forgotten products. This page was made with a lot of love and will live on for posterity. What to say, we're sentimental people. 😔
While this product is gone forever, here are others we recommend
Why FiiO is Special
Designed in China
Established & Reputed
Trust us, our reputation speaks for itself 🏆!
I believe that when a brand has decades of proven excellence, you can invest with confidence knowing your purchase is backed by years of audio engineering expertise. These products come from manufacturers with extensive histories of innovation and unwavering commitment to sonic excellence. Think of them like luxury watch brands - their reputation has been earned through decades of consistent quality and innovation.
With their extensive history of innovation and countless satisfied customers worldwide, you can be confident your investment is backed by proven audio engineering expertise and industry leadership 📈.
When you see "🎖️ Established & Reputed" products, expect time-tested excellence from manufacturers who've consistently demonstrated mastery in audio engineering for generations.
Revered by Audiophiles
Audiophiles can be really picky 😤, and if the audiophile community says something sounds good, you can bet it's exceptional! I believe that earning audiophile reverence is like getting a standing ovation from music critics - it doesn't happen unless you've truly achieved something special. This audio gear has earned widespread acclaim from audiophiles worldwide, a community renowned for exacting standards and unwavering commitment to high-fidelity reproduction.
These discerning enthusiasts particularly value its extraordinary precision in sound reproduction and remarkable capability to create thoroughly immersive listening experiences. The audiophile community's endorsement carries significant weight because of their extensive experience with high-end equipment 🏆.
When you see "🙌🏻 Revered by Audiophiles" products, expect audiophile-grade excellence that satisfies even the most demanding listeners and consistently exceeds the highest standards.
Born in 2007
Why we love this DAC/Amp
Premium Economy
Sensible spending meets sophisticated quality in perfect harmony 💫.
I tend to describe premium economy products as finding that sweet spot where exceptional value meets refined performance. Think of it like business class comfort at economy prices - you're getting significantly more than what you paid for. These headphones deliver a refined listening experience that rivals more expensive alternatives, making them an intelligent choice for discerning listeners who appreciate both value and excellence.
This thoughtfully curated selection demonstrates our commitment to bringing you outstanding sound quality and robust construction without requiring a significant financial investment. Each product has been meticulously evaluated to ensure it delivers performance characteristics typically associated with higher price brackets.
When you see "💎 Premium Economy" products, expect refined audio experiences that bridge the gap between entry-level and high-end offerings, delivering impressive clarity and features at accessible price points.
Serious Audiophiles Only
For those who have ventured deep into high-fidelity audio 🎯, the pursuit of sonic excellence becomes an endless journey of discovery and refinement. I believe that serious audiophiles demand equipment that can satisfy the most exacting standards and deliver performance that pushes boundaries. These products represent the pinnacle of acoustic engineering, incorporating advanced technologies and meticulous craftsmanship that enable them to reproduce music with utmost fidelity.
Each product has undergone rigorous evaluation to ensure it delivers exceptional performance that discerning listeners demand, from precise frequency response to impeccable detail retrieval and sophisticated sound staging. These devices incorporate premium components and engineering excellence that justify their position at the apex of audio performance.
When you encounter "🦈 Serious Audiophiles Only" products, expect uncompromising performance that satisfies the most demanding requirements and elevates critical listening to new heights.
Audiophile Community Favourite
When I see a product that keeps coming up in forums, Reddit threads, and community meet-ups, I know it’s earned its place. "Audiophile Community Favourite" is our way of spotlighting the gear that real listeners — not just reviewers — swear by. 🦋
These are products that enjoy a sort of cult following for all the right reasons: consistently great tuning, build, and value. They're the kind of recommendations you'd get from a friend deep in the hobby. If you're the type who likes going with a proven crowd-pleaser, these picks are beloved by thousands of ears.
When you see '🦋 Audiophile Community Favourite' products, expect reliable recommendations backed by passionate users, often refined over years of trust and love from the community.
Our Team's Favourite
Cause after all, we are audiophiles first 🎧!
In my experience, when our entire team gets excited about something, you know it's genuinely exceptional. This audio gear has captured the hearts and minds of our seasoned experts, distinguishing itself as a standout favourite among people who test hundreds of products every year. Think of it like getting a unanimous recommendation from a panel of audio critics - when everyone agrees, you pay attention.
These selections have not only met but exceeded our rigorous standards, earning enthusiastic endorsement from our audio specialists who've tested everything from budget options to flagship models. When you choose these products, you're selecting gear that has been thoroughly vetted and passionately embraced by genuine experts 🏆.
When you choose "💙 Our Team's Favourite" products, expect expertly vetted excellence backed by genuine enthusiasm from people who live and breathe audio every day.
For Audiophiles at Home
I’ve always loved the ritual of coming home, settling into my favourite chair, and firing up a dedicated setup. Gear labelled For Audiophiles at Home is made for those moments — when you can really sit back and appreciate music in its purest form 🛋️. These products tend to be more powerful, larger, and often require wall power — perfect for a stationary rig.
Here’s the trade-off: these setups often involve external DACs, amps, or full-size headphones, which means more space, more power, but also more immersive listening. They shine when used in quiet environments, where detail, depth, and dynamics can truly be appreciated.
When you see '🏠 For Audiophiles at Home' products, expect: exceptional fidelity, stronger output, and the kind of soundstage that makes you never want to leave your listening chair.
Use Wirelessly with Bluetooth
I tend to describe Bluetooth audio as wireless freedom with fewer strings attached — literally. When you see Use Wirelessly with Bluetooth, it means you can pair your headphones or IEMs with phones, laptops, or even TVs — all without reaching for a cable 🎶. It’s convenient, clutter-free, and great for everyday listening.
What’s happening behind the scenes is your gear is using Bluetooth codecs like SBC, AAC, LDAC, or aptX to compress and transmit your music wirelessly. Better codecs mean higher quality and lower latency. Of course, there’s a trade-off — Bluetooth won’t match the quality of wired gear, but today’s advancements have made the gap much smaller than before.
When you see '✂️ Use Wirelessly with Bluetooth' products, expect: tangle-free convenience and solid sound quality — great for commuting, workouts, or casual listening.
Connect With Cable
In my experience, there’s still nothing like the dependability of a wired connection when it comes to audio 🎧. I love describing it as the direct flight of music — no delays, no turbulence. When a product says “Connect with Cable,” it means you’re getting the most reliable signal path, with zero wireless compression and minimal interference.
Here’s what’s actually happening: a physical cable transmits uncompressed analog or digital signals directly from your source to your gear. This results in lower latency, no signal drops, and consistently better sound — especially when paired with a good DAC or amp. It’s ideal for critical listening, gaming, and professional use. The trade-off? You’re tethered — but for a lot of audiophiles, that’s a small price to pay for sonic purity.
When you see '🔗 Connect With Cable' products, expect: pure, uninterrupted sound quality that lets your gear perform at its full potential — perfect for focused, high-fidelity listening.
Built like a Tank
Durability concerns? Rest assured 💪.
I tend to describe these products as audio equipment that's built to survive anything you can throw at them. These headphones incorporate high-grade metal components and reinforced design elements that ensure they can handle demanding conditions while maintaining structural integrity. Think of them as the military-grade vehicles of the audio world - over-engineered for reliability and built to last decades, not just years.
The metal construction provides exceptional strength and longevity while contributing to a premium feel that serious audio enthusiasts appreciate. Whether you're a professional who needs reliable daily-use equipment or someone who values long-term investment in audio gear 🏗️.
When you encounter "🪖 Built like a Tank" products, expect unmatched robustness and durability you can count on for years of intensive use.
Why it Sounds Amazing
DAC Chip
I like to say the DAC chip is the heart of any audio device — it’s the part that actually transforms digital files into music you can hear 🎧. Think of it like a chef decoding a recipe to create a delicious meal. The better the DAC chip, the more faithfully it translates your music. And in my experience, a great DAC can completely change how your headphones sound.
Now, here’s what’s actually happening: a Digital-to-Analog Converter (DAC) takes digital signals (your MP3s, FLACs, or streams) and converts them into an analog waveform your ears can enjoy. Different DAC chips — like those from ESS, AKM, or Cirrus Logic — offer their own sound signatures, levels of clarity, and noise performance. A good DAC ensures accurate timing, minimal distortion, and exceptional resolution.
When you see '⚙️ DAC Chip' products, expect: clean, detailed audio and better synergy with high-quality headphones — perfect for anyone upgrading from average sound to audiophile quality.
Power Output
I like to think of power output in audio gear like engine horsepower, it determines how much muscle your setup really has 💪. Whether you’re trying to drive a pair of power-hungry planar headphones or just want headroom for dynamic peaks, power output is the spec you want to check first.
Technically, it refers to the amount of electrical power (measured in mW or Watts) an amp or DAC/Amp combo can deliver to your headphones. More power means better control, improved dynamics, and the ability to handle demanding gear without distortion. But more isn’t always better, too much power with sensitive IEMs can introduce hiss or harshness.
When you see '🚀 Power Output' products, expect: strong driving capability, better dynamics, and optimal performance with headphones that need serious juice to shine.
Balanced Output
I often say balanced output is like using both hands to carry something heavy — it distributes power evenly and keeps things stable. In audio gear, balanced output helps reduce unwanted noise and interference, especially over longer cables. Think of it as a cleaner, more efficient way to transmit your music, ideal for anyone using high-end DACs, amps, or studio-grade headphones 🎧. You’ll typically find it on gear with XLR or 4.4mm connectors, and it's a must-have if you’re chasing that ultra-clean signal path.
Here’s what’s actually happening: a balanced output uses two separate signals, one inverted, so when interference is picked up along the cable, it gets cancelled out when the signals are recombined. The result? Cleaner audio, better dynamic range, and more power output — especially when paired with balanced headphones. The trade-off? You’ll need gear that supports balanced connections on both ends to really enjoy the benefits.
When you see '⚖️ Balanced Output' products, expect: ultra-low noise, more headroom, and better synergy with high-impedance headphones or sensitive IEMs — ideal for serious listening setups.
Decodes Upto
When I see "Decodes up to" listed in product specs, I think of it like a music translator that speaks more languages than you’ll ever need. It tells you how far a DAC or audio device can go in handling hi-res formats—think PCM, DSD, or MQA—and at what resolution. 🧠🎶
Technically, this refers to the maximum bit depth and sample rate a DAC can process—like 32-bit/768kHz PCM or DSD512. The higher these numbers, the more detailed and lifelike the audio can potentially sound. But remember, real-world improvements depend on the recording quality and your headphones, not just specs alone.
At last, an all-in-one device that doesn't compromise on finer details or frequency response. The FiiO K9 Pro ESS is skilfully designed, intelligently engineered, and delivers exceptional sound quality. It outshines even higher-priced units while maintaining minimal distortion and noise.

About RAGHAV SOMANI
Raghav Somani is the Founder & CEO of Headphone Zone. An avid audiophile and musician since 2008, his choice of headphones include STAX Electrostats, Audeze LCD 3, and for music on the go, the JH Audio Roxanne + Astell&Kern SP1000 is never too far away. On his playlist, you'll find A.R. Rahman, Michael Jackson, and the Eagles.
DESCRIPTION
FIIO PRESENTS THE UPGRADED K9 PRO EQUIPPED WITH A DUAL ESS SABRE CHIP FOR PRISTINE AUDIO
FiiO introduces the flagship desktop DAC and Amplifier that houses the best components and features the latest engineering innovations. The team at FiiO has equipped the K9 Pro ESS with two high-performance ES9038PRO DAC chips made by ESS Sabre. The ES9038 Pro is a flagship-grade 8-channel DAC chip that is capable of providing ground-breaking performance in decoding high-resolution audio signals and offers 7 digital filters. FiiO has upgraded the K9 Pro ESS from the K9 Pro in terms of DAC count, the K9 Pro had only a single AK4499 DAC, and the latest K9 Pro has dual ES9038 Pro DAC Chips. With the help of this new DAC chipset, the K9 Pro ESS achieves ultra-low THD+N(<0.00025%) and high SNR(>129dB) ratings ensuring a super-clean performance.




EXEMPLARY DUAL THX AAA AMPLIFIER CIRCUIT DELIVERING AMPLE POWER TO DRIVE ANY HEADPHONE
FiiO K9 Pro ESS not only acts as a high performing DAC but also offers Amplification functions. Equipped with a pair of THX AAA 788+ chips, the K9 Pro ESS provides vivid details and dynamics whether you are using low or high-impedance headphones. The K9 Pro ESS with the THX AAA 788+ chip can output up to 46Vpp transients while driving high-impedance loads and up to an undistorted 2W when pushing low-impedance loads. The embedded THX AAA chip can produce an undistorted 1100mW under a 300ohm load and an undistorted 2100mW under a 32ohm load, 50% higher than the original THXAAA 788 amplifier chips with higher heat dissipation efficiency.




FULLY DIFFERENTIAL AND BALANCED DESIGN WITH A DUAL FEMTOSECOND CLOCK AND SIX-STAGE CIRCUITRY
The K9 Pro ESS is engineered to offer the best audio performance. To achieve this, a fully differential and truly balanced design is utilised for the K9 Pro ESS. Such a design ensures minimal interference between different components to fully maintain all details and the large dynamic swings in music for unmatched sound quality. Differential signals go through the four channels of the DAC, four channels of volume adjustment, and four channels of Amp for a truly balanced design. It also has a six-stage audio circuitry to ensure the users get the best possible sound performance. The analogue and digital circuits have separated paths with partitions for clean performance. Using an ultra-precise clock management system, the K9 Pro ESS can maintain maximum quality no matter the source. Dual asynchronous femtosecond clocks decode USB and Bluetooth sources, while automatic PLL clocks decode optical and coaxial sources.




FAST AND RELIABLE HI-RES BLUETOOTH CONNECTIVITY WITH LOSSLESS MQA DECODING CAPABILITY
Like every aspect of the FiiO K9 Pro ESS, it features the latest in Bluetooth technology to offer Hi-Res quality audio wirelessly. The FiiO K9 Pro ESS employs the Qualcomm QCC 5124 to handle Bluetooth connectivity, with support for formats such as AAC, SBC, LDAC, aptX, aptX LL, 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. With the latest technologies found in the K9 Pro ESS, it supports the unfolding of MQA tracks, allowing you to listen to high-resolution audio files that are not only compact but also retain the master-level sound quality that brings you directly into the recording studio. Apart from these high-res MQA Support, the K9 Pro also supports high-res 32-Bit/384kHZ PCM as well as native DSD256 decoding.


ADVANCED POWER DELIVERY WITH LDO’S AND PORTIONED CHASSIS DESIGN FOR LINEAR TRANSMISSION
The FiiO K9 Pro ESS features a highly regarded linear power supply. 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 for the whole system. The chassis of the K9 Pro ESS uses a portioned layout, wherein not only the power supply and signals are separated, but the analogue signal loop is also put in an independent section, guaranteeing the integrity of the audio signal being processed. The digital portions of the K9 Pro receive power separately from the analogue parts for effective shielding against audio interference between the two circuits. In each stage of the audio circuit, ultra-low-noise LDO is employed for voltage regulation. No expense was spared in ensuring a clean power supply, with the K9 Pro ESS in total having a substantial amount of 20 LDOs.


THREE WAY GAIN SETTINGS WITH ACCURATE VOLUME ADJUSTMENTS BASED ON ADC CURVE RECONSTRUCTION




OFFERING MULTIPLE CONNECTIVITY PORTS HOUSED IN A ELEGANT AND DURABLE ALUMINIUM CHASSIS
The simple, yet elegant all-aluminium black exterior of the FiiO K9 Pro ESS is anodised 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 FiiO K9 Pro ESS is the very definition of a reliable and loyal music partner in your collection. The FiiO K9 Pro ESS also comes with multiple connectivity options for easy connectivity. The front side features - XLR-4Pin, 4.4mm Balanced, 6.35mm Single Ended headphone outputs and the rear side features - 4.4mm Balanced Line In, Coaxial, optical, RCA, XLR out for more convenient connections to external amps and speakers. There is also a USB Type-C port on the side for easy connectivity.




ELEGANT USER INTERFACE WITH DEDICATED APP AND METAL SWITCHES TO CONTROL VARIOUS FEATURES
The FiiO K9 Pro ESS comes with a dedicated app to control various features of the device. Built-In Bluetooth Low Energy (BLE) technology allows you to use the FiiO Control App to control functions like channel balance and sleep timer, even when not in Bluetooth mode. This feature is handy and offers convenience. Controls are clearly and intuitively laid out for an effortless experience. Metal switches are used for controlling input selection and gain level to help you easily and quickly switch to your desired method of listening. The stainless-steel volume knob blends seamlessly with the alluvium 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 current playing sampling rate. The FiiO K9 Pro also comes bundled with a custom stand that reduces the amount of space the K9 ESS Pro 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.




SPECS
MODEL | K9 Pro |
COLOR | Black |
WEIGHT | ≈2750g |
GAIN | L/M/H |
BLUETOOTH FORMAT INDICATION | Supported |
FIRMWARE UPGRADE | System firmware and Bluetooth version can be upgraded via USB |
LOW BATTERY REMINDER | NA |
BLUETOOTH TRANSMISSION | NA |
BLUETOOTH FORMAT INDICATOR | SBC: blue, AAC: cyan, aptX HD: yellow, aptX: purple, aptX LL: purple, LDAC: white, atpX Adaptive: green |
MAXIMUM SUPPORTED SAMPLING RATE | 384kHz-32bit/DSD256(USB DAC) 192kHz-24bit (coaxial) 96KHz-24bit (optical) |
HARDWARE SOLUTION | DAC: ES9038PRO*2, USB: XMOS XUF208, Bluetooth: QCC5124, LPF: OPA1612 * 2, volume IC: NJU72315 * 2, AMP: THX AAA788+ * 2, linear transformer |
VOLUME SCROLL | Potentiometer+ADC Sampling |
CHANNEL BALANCE | L12~R12 (0.5dB per level) |
FIIO CONTROL | Supported |
SAMPLING RATE INDICATION | Supported |
DEEP STANDBY | Long press the multi-function button for about 3s |
BLUETOOTH RECEIVER (5.0) | AAC/SBC/aptX/aptX LL/aptX HD/LDAC/atpX Adaptive |
DIMENSIONS | ≈200x224.5x72mm (excluding feet) |
CHARGING INDICATOR | NA |
RECOMMENDED HEADPHONE IMPEDANCE | 16~600 Ω |
BUTTON | Physical key + toggle switch |
SINGLE-ENDED LINE INPUT INTERFACE | RCA socket |
SPDIF IN | Optical fiber socket |
BALANCED OUTPUT INTERFACE | 4.4mm socket, XLR4 balanced socket |
BALANCED LINE OUTPUT INTERFACE | XLR3 balanced socket |
USB | Type-C, USB B (data transmission) |
BALANCED LINE INPUT INTERFACE | 4.4mm balanced socket |
DIGITAL COAXIAL INPUT INTERFACE | RCA socket |
HEADPHONE OUTPUT INTERFACE | Standard 6.35 mm socket |
SINGLE-ENDED LINE OUTPUT INTERFACE | RCA socket |
POWER SUPPLY | AC 110-115V~/AC 220-230V~ (Recommended) |
CHARGING TIME | NA |
BATTERY CAPACITY | NA |
PO BATTERY LIFE | NA |
THD+N | <0.00042%(1kHz/10kΩ/dbA) |
CROSSTALK | ≥115dB (1kHz/10kΩ) |
FREQUENCY RESPONSE | 20Hz~20kHz (-3dB) |
SNR | ≥123dB (dbA) |
NOISE LEVEL | <1.9μV(dbA) |
LINE LEVEL | 2.5Vrms (1kHz/10kΩ) |
THD+N | <0.00025%(1kHz/10kΩ/dbA) |
CROSSTALK | ≥125dB (1kHz/10kΩ) |
FREQUENCY RESPONSE | 20Hz~50kHz (-1.5dB) |
SNR | ≥128dB (dbA) |
NOISE LEVEL | <1.9μV(dbA) |
LINE LEVEL | 5Vrms (1kHz/10kΩ) |
CONTINUOUS UNDISTORTED OUTPUT POWER 1 | ≥1.1W(16Ω / THD+N<1%, AUX IN) |
CONTINUOUS UNDISTORTED OUTPUT POWER 2 | ≥2.1W(32Ω/THD+N<1%,AUX IN) |
CONTINUOUS UNDISTORTED OUTPUT POWER 3 | ≥281mW(300Ω / THD+N<1%,AUX IN) |
NOISE FLOOR | <2μV(dbA,AUX IN) <3μV(dbA,UAC/SPDIF/BT IN) |
FREQUENCY RESPONSE | 20 Hz~50kHz (-1.5dB) |
OUTPUT IMPEDANCE | <1Ω(32Ω) |
CROSSTALK | ≥75dB (1 kHz/32Ω,AUX IN) |
THD+N | <0.00033% (1 kHz/32Ω/dbA) |
SNR | ≥129dB (dbA) |
MAX OUTPUT VOLTAGE | >26Vp-p |
CONTINUOUS UNDISTORTED OUTPUT POWER 1 | ≥1.1W(16Ω / THD+N<1%) |
CONTINUOUS UNDISTORTED OUTPUT POWER 2 | ≥2.1W(32Ω /THD+N<1%) |
CONTINUOUS UNDISTORTED OUTPUT POWER 3 | ≥1.1W(300Ω / THD+N<1%) |
NOISE FLOOR | <3μV(dbA, AUX IN) 4.5uV(dbA,UAC/SPDIF/BT) |
FREQUENCY RESPONSE | 20Hz~50kHz (-3dB) |
OUTPUT IMPEDANCE | <1Ω(32Ω) |
CROSSTALK | ≥114dB (1 kHz,AUX IN) |
THD+N | <0.0003% (1 kHz/32Ω/dbA) |
SNR | ≥123dB (dbA) |
MAX OUTPUT VOLTAGE | >52Vp-p |
BOX CONTENT | 1. FiiO K9 Pro ESS |
2. Power Cord | |
3. Square port USB data cable | |
4. Bluetooth antenna | |
5. 6.35mm male to 3.5mm female Headphone jack adapter | |
6. Quick start | |
7. Warranty card | |
8. Instruction card for voltage selection | |
9. Fuse | |
10. Voltage protection plug |
![]() Flagship Desktop DAC & Amplifier
|
FIIO PRESENTS THE UPGRADED K9 PRO EQUIPPED WITH A DUAL ESS SABRE CHIP FOR PRISTINE AUDIO
FiiO introduces the flagship desktop DAC and Amplifier that houses the best components and features the latest engineering innovations. The team at FiiO has equipped the K9 Pro ESS with two high-performance ES9038PRO DAC chips made by ESS Sabre. The ES9038 Pro is a flagship-grade 8-channel DAC chip that is capable of providing ground-breaking performance in decoding high-resolution audio signals and offers 7 digital filters. FiiO has upgraded the K9 Pro ESS from the K9 Pro in terms of DAC count, the K9 Pro had only a single AK4499 DAC, and the latest K9 Pro has dual ES9038 Pro DAC Chips. With the help of this new DAC chipset, the K9 Pro ESS achieves ultra-low THD+N(<0.00025%) and high SNR(>129dB) ratings ensuring a super-clean performance.




EXEMPLARY DUAL THX AAA AMPLIFIER CIRCUIT DELIVERING AMPLE POWER TO DRIVE ANY HEADPHONE
FiiO K9 Pro ESS not only acts as a high performing DAC but also offers Amplification functions. Equipped with a pair of THX AAA 788+ chips, the K9 Pro ESS provides vivid details and dynamics whether you are using low or high-impedance headphones. The K9 Pro ESS with the THX AAA 788+ chip can output up to 46Vpp transients while driving high-impedance loads and up to an undistorted 2W when pushing low-impedance loads. The embedded THX AAA chip can produce an undistorted 1100mW under a 300ohm load and an undistorted 2100mW under a 32ohm load, 50% higher than the original THXAAA 788 amplifier chips with higher heat dissipation efficiency.




FULLY DIFFERENTIAL AND BALANCED DESIGN WITH A DUAL FEMTOSECOND CLOCK AND SIX-STAGE CIRCUITRY
The K9 Pro ESS is engineered to offer the best audio performance. To achieve this, a fully differential and truly balanced design is utilised for the K9 Pro ESS. Such a design ensures minimal interference between different components to fully maintain all details and the large dynamic swings in music for unmatched sound quality. Differential signals go through the four channels of the DAC, four channels of volume adjustment, and four channels of Amp for a truly balanced design. It also has a six-stage audio circuitry to ensure the users get the best possible sound performance. The analogue and digital circuits have separated paths with partitions for clean performance. Using an ultra-precise clock management system, the K9 Pro ESS can maintain maximum quality no matter the source. Dual asynchronous femtosecond clocks decode USB and Bluetooth sources, while automatic PLL clocks decode optical and coaxial sources.




FAST AND RELIABLE HI-RES BLUETOOTH CONNECTIVITY WITH LOSSLESS MQA DECODING CAPABILITY
Like every aspect of the FiiO K9 Pro ESS, it features the latest in Bluetooth technology to offer Hi-Res quality audio wirelessly. The FiiO K9 Pro ESS employs the Qualcomm QCC 5124 to handle Bluetooth connectivity, with support for formats such as AAC, SBC, LDAC, aptX, aptX LL, 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. With the latest technologies found in the K9 Pro ESS, it supports the unfolding of MQA tracks, allowing you to listen to high-resolution audio files that are not only compact but also retain the master-level sound quality that brings you directly into the recording studio. Apart from these high-res MQA Support, the K9 Pro also supports high-res 32-Bit/384kHZ PCM as well as native DSD256 decoding.


ADVANCED POWER DELIVERY WITH LDO’S AND PORTIONED CHASSIS DESIGN FOR LINEAR TRANSMISSION
The FiiO K9 Pro ESS features a highly regarded linear power supply. 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 for the whole system. The chassis of the K9 Pro ESS uses a portioned layout, wherein not only the power supply and signals are separated, but the analogue signal loop is also put in an independent section, guaranteeing the integrity of the audio signal being processed. The digital portions of the K9 Pro receive power separately from the analogue parts for effective shielding against audio interference between the two circuits. In each stage of the audio circuit, ultra-low-noise LDO is employed for voltage regulation. No expense was spared in ensuring a clean power supply, with the K9 Pro ESS in total having a substantial amount of 20 LDOs.


THREE WAY GAIN SETTINGS WITH ACCURATE VOLUME ADJUSTMENTS BASED ON ADC CURVE RECONSTRUCTION




OFFERING MULTIPLE CONNECTIVITY PORTS HOUSED IN A ELEGANT AND DURABLE ALUMINIUM CHASSIS
The simple, yet elegant all-aluminium black exterior of the FiiO K9 Pro ESS is anodised 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 FiiO K9 Pro ESS is the very definition of a reliable and loyal music partner in your collection. The FiiO K9 Pro ESS also comes with multiple connectivity options for easy connectivity. The front side features - XLR-4Pin, 4.4mm Balanced, 6.35mm Single Ended headphone outputs and the rear side features - 4.4mm Balanced Line In, Coaxial, optical, RCA, XLR out for more convenient connections to external amps and speakers. There is also a USB Type-C port on the side for easy connectivity.




ELEGANT USER INTERFACE WITH DEDICATED APP AND METAL SWITCHES TO CONTROL VARIOUS FEATURES
The FiiO K9 Pro ESS comes with a dedicated app to control various features of the device. Built-In Bluetooth Low Energy (BLE) technology allows you to use the FiiO Control App to control functions like channel balance and sleep timer, even when not in Bluetooth mode. This feature is handy and offers convenience. Controls are clearly and intuitively laid out for an effortless experience. Metal switches are used for controlling input selection and gain level to help you easily and quickly switch to your desired method of listening. The stainless-steel volume knob blends seamlessly with the alluvium 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 current playing sampling rate. The FiiO K9 Pro also comes bundled with a custom stand that reduces the amount of space the K9 ESS Pro 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.




MODEL | K9 Pro |
COLOR | Black |
WEIGHT | ≈2750g |
GAIN | L/M/H |
BLUETOOTH FORMAT INDICATION | Supported |
FIRMWARE UPGRADE | System firmware and Bluetooth version can be upgraded via USB |
LOW BATTERY REMINDER | NA |
BLUETOOTH TRANSMISSION | NA |
BLUETOOTH FORMAT INDICATOR | SBC: blue, AAC: cyan, aptX HD: yellow, aptX: purple, aptX LL: purple, LDAC: white, atpX Adaptive: green |
MAXIMUM SUPPORTED SAMPLING RATE | 384kHz-32bit/DSD256(USB DAC) 192kHz-24bit (coaxial) 96KHz-24bit (optical) |
HARDWARE SOLUTION | DAC: ES9038PRO*2, USB: XMOS XUF208, Bluetooth: QCC5124, LPF: OPA1612 * 2, volume IC: NJU72315 * 2, AMP: THX AAA788+ * 2, linear transformer |
VOLUME SCROLL | Potentiometer+ADC Sampling |
CHANNEL BALANCE | L12~R12 (0.5dB per level) |
FIIO CONTROL | Supported |
SAMPLING RATE INDICATION | Supported |
DEEP STANDBY | Long press the multi-function button for about 3s |
BLUETOOTH RECEIVER (5.0) | AAC/SBC/aptX/aptX LL/aptX HD/LDAC/atpX Adaptive |
DIMENSIONS | ≈200x224.5x72mm (excluding feet) |
CHARGING INDICATOR | NA |
RECOMMENDED HEADPHONE IMPEDANCE | 16~600 Ω |
BUTTON | Physical key + toggle switch |
SINGLE-ENDED LINE INPUT INTERFACE | RCA socket |
SPDIF IN | Optical fiber socket |
BALANCED OUTPUT INTERFACE | 4.4mm socket, XLR4 balanced socket |
BALANCED LINE OUTPUT INTERFACE | XLR3 balanced socket |
USB | Type-C, USB B (data transmission) |
BALANCED LINE INPUT INTERFACE | 4.4mm balanced socket |
DIGITAL COAXIAL INPUT INTERFACE | RCA socket |
HEADPHONE OUTPUT INTERFACE | Standard 6.35 mm socket |
SINGLE-ENDED LINE OUTPUT INTERFACE | RCA socket |
POWER SUPPLY | AC 110-115V~/AC 220-230V~ (Recommended) |
CHARGING TIME | NA |
BATTERY CAPACITY | NA |
PO BATTERY LIFE | NA |
THD+N | <0.00042%(1kHz/10kΩ/dbA) |
CROSSTALK | ≥115dB (1kHz/10kΩ) |
FREQUENCY RESPONSE | 20Hz~20kHz (-3dB) |
SNR | ≥123dB (dbA) |
NOISE LEVEL | <1.9μV(dbA) |
LINE LEVEL | 2.5Vrms (1kHz/10kΩ) |
THD+N | <0.00025%(1kHz/10kΩ/dbA) |
CROSSTALK | ≥125dB (1kHz/10kΩ) |
FREQUENCY RESPONSE | 20Hz~50kHz (-1.5dB) |
SNR | ≥128dB (dbA) |
NOISE LEVEL | <1.9μV(dbA) |
LINE LEVEL | 5Vrms (1kHz/10kΩ) |
CONTINUOUS UNDISTORTED OUTPUT POWER 1 | ≥1.1W(16Ω / THD+N<1%, AUX IN) |
CONTINUOUS UNDISTORTED OUTPUT POWER 2 | ≥2.1W(32Ω/THD+N<1%,AUX IN) |
CONTINUOUS UNDISTORTED OUTPUT POWER 3 | ≥281mW(300Ω / THD+N<1%,AUX IN) |
NOISE FLOOR | <2μV(dbA,AUX IN) <3μV(dbA,UAC/SPDIF/BT IN) |
FREQUENCY RESPONSE | 20 Hz~50kHz (-1.5dB) |
OUTPUT IMPEDANCE | <1Ω(32Ω) |
CROSSTALK | ≥75dB (1 kHz/32Ω,AUX IN) |
THD+N | <0.00033% (1 kHz/32Ω/dbA) |
SNR | ≥129dB (dbA) |
MAX OUTPUT VOLTAGE | >26Vp-p |
CONTINUOUS UNDISTORTED OUTPUT POWER 1 | ≥1.1W(16Ω / THD+N<1%) |
CONTINUOUS UNDISTORTED OUTPUT POWER 2 | ≥2.1W(32Ω /THD+N<1%) |
CONTINUOUS UNDISTORTED OUTPUT POWER 3 | ≥1.1W(300Ω / THD+N<1%) |
NOISE FLOOR | <3μV(dbA, AUX IN) 4.5uV(dbA,UAC/SPDIF/BT) |
FREQUENCY RESPONSE | 20Hz~50kHz (-3dB) |
OUTPUT IMPEDANCE | <1Ω(32Ω) |
CROSSTALK | ≥114dB (1 kHz,AUX IN) |
THD+N | <0.0003% (1 kHz/32Ω/dbA) |
SNR | ≥123dB (dbA) |
MAX OUTPUT VOLTAGE | >52Vp-p |
BOX CONTENT | 1. FiiO K9 Pro ESS |
2. Power Cord | |
3. Square port USB data cable | |
4. Bluetooth antenna | |
5. 6.35mm male to 3.5mm female Headphone jack adapter | |
6. Quick start | |
7. Warranty card | |
8. Instruction card for voltage selection | |
9. Fuse | |
10. Voltage protection plug |
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Don't sweat it, this
FiiO - K9 Pro ESS comes with a 1 Year warranty
from FiiO that covers manufacturing defects.
All products featured on Headphone Zone are backed by an original manufacturer's warranty.
Read more about FiiO's warranty in India.


GOLD AWARD
SoundNews.net
Mar, 2022

HFN Recommended
Headfonia
April, 2022

TR Recommended
Trusted Reviews
June, 2022
"If the M17 was out of your budget then the FiiO K9 Pro ESS is the more affordable and wiser choice for headphone users. You get a very similar coloration and presentation style for one-third of the price."
Read More"The K9 Pro ESS is a very impressive DAC & AMP and FiiO nailed almost everything about it. I can see many reasons why FiiO has managed to build such a successful device. I highly recommend giving the FiiO K9 Pro a try."
Read More"The K9 Pro ESS is a very impressive DAC & AMP and FiiO nailed almost everything about it. I can see many reasons why FiiO has managed to build such a successful device. I highly recommend giving the FiiO K9 Pro a try."
Read More"Yes, it’s big and heavy for a product that thinks it should live on your desktop. But the FiiO K9 Pro ESS’s functionality and sonic expertise is such that you might, if necessary. Speedy, deft and endlessly informative sound."
Read More