FiiO K9 DAC/Amplifier Review



FiiO K9 All-in One Headphone DAC/Amplifier Review



FiiO released the K9 Pro and K9 Pro ESS back in 2021, which are both Desktop type DAC/Amplifiers that have got a very positive feedback from the audiophile community. The K9 on the other hand is the company’s latest product that has been released to fill the gap in the price range of 300 to 600 USD. The K9 borrows critically acclaimed technologies from the K9 PRO/K9 PRO ESS and integrates some new components in order to archive a more affordable price.

The new K9 features some impressive hardware specs such like two ES9068AS DAC chips, a fully balanced THX AAA-788+ amp module, Qualcomm’s new QCC5124 Bluetooth chip, a mammoth type 6-stage circuit and Dual low-noise linear+isolated digital power supplies. The device is equipped with a wide variety of Digital & Analog interfaces including USB, Optical, Coaxial, RCA and 4.4mm BAL inputs and XLR-4 BAL, 6.35mm Single-Ended and 4.4mm Balanced outputs.



I would like to thank FiiO for providing me the K9 Desktop DAC/Amplifier as review sample. I am not affiliated with FiiO beyond this review and these words reflect my true and unaltered, opinions about the product.


Price & Availability:

The actual price for the FiiO K9 Desktop Headphone DAC/Amplifier is 499.99 US$. More information’s can be found under the link below;


Package & Accessories:

The FiiO K9 came inside a square shaped black cardboard box that has a fancy design. It sports the illustration and some product related brandings with an iridescent finish on its surface.

The box of the K9 Headphone DAC/Amplifier contains the following items:

  • 1 x FiiO K9 Desktop Headphone DAC/Amplifier
  • 1 x USB-A to USB-B cable
  • 1 x Power Cable
  • 1 x Power Adapter
  • 1 x 6.35mm Headphone Adapter
  • 1 x Stand
  • 6 x Feet Pads
  • 1 x Voltage Selection Card
  • 1 x User Manual & Warranty card


Design & Build Quality:

The FiiO K9 is a Desktop type All-in One DAC & Headphone Amplifier that immediately impressed me with its clean, esthetic and highly robust appearance. The K9 features a solid CNC machined Aluminum unibody with a black anodized finish. The device has dimensions of about 200×224.5x72mm (excluding feet) and weights approx 2660grams.

On the front panel of the K9 are the analog outputs, multiple control buttons/switches and a large volume knob.

The left area of the front panel sports the XLR-4 BAL, 6.35mm Single Ended and 4.4mm Balanced headphone outputs.

Right at the center of the panel is a large volume knob (potentiometer) that features an eye catching RGB status indicator in form of a ring that surrounds the knob. The status indicator glows up in various colors depending of the codec and operating status of the device.

The left area of the front panel is equipped with the Output & Gain switches, the Input + Power/Mute buttons and 5 small LED lights that shows the actual selected input (USB/OPT/COAX/LINE/BT) mode of the K9.

Both the left and right surface of the K9 sports fairly large ventilation outlets in order to cool down the heat created by the internals of the device.

On the top of the DAC/Amplifier are the FiiO brand logo and a label with the Hi-Res Audio & THX Technology branding.

The rear panel is the location where you can find the Power Input Port, Main Power Button and various Digital & Analog Input interfaces, such like USB, Optical, Coaxial & Bluetooth (Antenna) and 4.4mm BAL, RCA and XLR.

At the bottom of the main body are four stands that do have rubber isolations feet’s and a voltage selector.

The K9 comes with a small stand in order to place the device vertically that will safe space and give the device a fancy look.


Technical Specifications:

  • Model                         : K9
  • DAC                           : ES9068AS*2
  • Decoding chip            : XMOS XUF 208
  • Amplifier                     : Dual THX AAA 788+
  • Bluetooth chip            : QCC5124, Bluetooth 5.1
  • BT formats                 : LDAC/atpX Adaptive/aptX HD/aptX/aptX LL/AAC/SBC
  • Outputs                      : 6.35mm/4.4mm/XLR-4/RCA/XLR
  • Inputs                          : USB/OPT/COAX/RCA/4.4mm
  • Output power 1          : L+R≥2000mW+2000mW (32Ω balanced/THD+N<1%)
  • Output power 2          : L+R≥780mW+780mW (300Ω balanced/THD+N<1%)
  • SNR                           : ≥124dB (A-weighted, UAC)
  • Noise floor                  : PO<4.8μV (A-weighted, UAC); BAL<7.1μV (UAC, max volume)
  • Output impedance     : <1Ω (32Ω load)
  • Weight                        : About 2660g
  • Dimensions                : 200×224.5x72mm (excluding feet)



The FiiO K9 is a feature rich All-in One desktop type DAC & Headphone Amplifier that has some impressive hardware components under the hood.


DAC (Digital to Analog Converter):

The FiiO K9 is equipped with a Dual ES9068AS DAC chipset that delivers a pretty good SNR (Signal to Noise Ratio) value of 124dB. The ES9068AS handles up to 32-bit 768 kHz PCM and Native DSD decoding up to DSD256.

Analog Outputs & Amplification (THX AAA 788+):

The FiiO K9 features a pretty powerful amplifier design with a true balanced architecture. The device is equipped with a wide variety of analog output interfaces including 1x 6.35mm Single-Ended, 1x 4.4mm Balanced (TRRRS) and 1x XLR-4 BAL output.

Another highlight of K9 is its THX AAA™ “Achromatic Audio Amplifier” design that was used to create a clean and powerful analog output. The K9 is able to output 42Vpp transients when driving high-impedance headphones while the non-distortion power goes to 2000mW (32Ω/1%) when driving low-impedance headphones and the indicators are not very different from the flagship K9 Pro series.

The K9 is a sophisticated DAC/Amplifier that offers a 6-level audio process, including I/V conversion, LPF filter, electronic volume adjustment, voltage emitter follower, front amplifier and finale driven stage. The result is an ultra clean and dark background atmosphere, which makes the device ideal for both sensitive IEM’s and harder to drive full sized headphones.


XMOS XU208 for Native DSD:

The FiiO K9 is equipped with the XMOS XUF208 decoder chip that uses dual clock management in order to handle various music formats. XUF208 USB chip handles up to 384kHz-32bit PCM and Native DSD decoding up to DSD256 in USB DAC Mode.

The RGB LED Indicator that surrounds the Potentiometer shows up the following sampling rates:

  • Blue     :44.1KHz/48KHz
  • Yellow :88.2/96/176.4/192/352.8/384KHz
  • Green  :DSD64/128/256



Bluetooth Connectivity:

The FiiO K9 features Qualcomm’s latest QCC5124 Bluetooth SoC, which supports BT codes such like LDAC, APTX HD, AptX LL, AptX Adaptive, SBC and AAC. The Bluetooth operating distance of the K9 is flawlessly up to a distance of 12 meters when paired with my Samsung Galaxy S22 Ultra in an open environment.

The RGB LED Indicator shows up the following sampling rates: 

  • Blue                : SBC
  • Turquoise        : AAC
  • White              : LDAC
  • Yellow             : aptX HD
  • Purple             : aptX/aptX LL
  • Green             : aptX Adaptive



Through the FiiO Control app, you can quickly switch between 7 music tuning styles preset on the K9. You have also the option to adjust up to 3 self-defined PEQ (Parametric Equalizer) settings. Please note that this features is only valid for Bluetooth decoding.


Equipment’s used for this review:

  • DAC/Amplifier’s       : FiiO K9
  • Sources                     : ASUS TUF FX504G, FiiO M11 Plus ESS
  • Headphones             : FiiO FT3, HiFiMAN Edition XS
  • IEM’s                          : FiiO FH7S, Westone Audio MACH60, Meze Audio RAI Penta


Albums & tracks used for this review:

  • Adele – My Little Love (Dezzer HiFi)
  • Randy Crawford – On Day I Will Fly Away (Flac 16bit/44.1kHz)
  • Hayley Westenra – Odyssey Album (Dezzer HiFi)
  • Dionne Warwick – Walk On By (Flac 16bit/44.1kHz)
  • Sarah McLachlan – Angel (Flac 24bit/48kHz)
  • Sertap Erener – Aşk (Flac 16bit/44.1kHz)
  • Edith Piaf – Non Je Ne Regrette Rien (Flac 16bit/44.1kHz)
  • Diana Krall – So Wonderful (DSF)
  • Aretha Franklin – I Say A Little Payer (Flac 24bit/96kHz)
  • Sonya Yoncheva – (Giuseppe Verdi) II Trovatore, ActI (Flac 24bit/96kHz)
  • George Michael – Don’t Let the Sun Go Down on Me (Flac 24bit/192kHz)
  • David Bowie – Heroes (Flac 24bit/192kHz)
  • Elton John – Rocket Man ((Flac 24bit/96kHz)
  • Barry White – Just The Way You Are (Flac 24bit/48kHz)
  • Isaac Hayes – Walk On By (Flac 16bit/44.1kHz)
  • Sting – Englishman in New York – (Flac 24bit/48kHz)
  • Eric Clapton – Wonderful Tonight (Flac 24bit/96kHz)
  • B. King – Riding With The King (Tidal Hi-Fi)
  • Dave Gahan – Kingdom (Tidal Hi-Fi)
  • U2 – Sunday Bloody Sunday (Flac 16bit/44.1kHz)
  • Bro Safari, UFO! – Drama (Deezer HiFi)
  • Armin Van Buuren – Vini Vici (Flac 16bit/44.1kHz)
  • Daft Punk – Doin’ it Right (Flac 24bit/96kHz)
  • Jo Blankenburg – Meraki (Spotify)
  • Lorde – Royals (Flac 24bit/48kHz)
  • Massive Attack – Angel (Flac 24bit/48kHz)
  • Toutant – Rebirth (Deezer HiFi)
  • Gogo Penguin – Raven (Flac 24bit/192kHz)
  • Gogo Penguin – Murmuration (Flac 24bit/192kHz)
  • Portishead – It Could Be Sweet (Spotify)
  • Max Richter – On the Nature of Daylight (Flac 24bit/96kHz)
  • Charly Antolini – Duwadjuwandadu (Flac 24bit/192kHz)
  • Ferit Odman – Look, Stop & Listen (Flac 24bit/192kHz)
  • Chopin – Nocturn No. 20 In C-Sharp Minor (Flac 16bit/44.1kHz)
  • Fazıl Say – Nazım Oratoryosu (Live) (Flac 16bit/44.1kHz)
  • Vivaldi – Le QuarttroStagioni “The Four Season” (Deezer HiFi)
  • Otto Liebert & Luna Negra – The River (Flac 24bit/192kHz)
  • Lunatic Soul – The Passage (Flac 16bit/44.1kHz)
  • Deftones – My Own Summer (Shove it) (Flac 16bit/44.1kHz)
  • Metallica – Sad but True (Flac 24bit/96kHz)
  • Metallica – Master of Puppets (Flac 24bit/96kHz)
  • Opeth – Windowpane (Flac 16bit/44.1kHz)
  • Megadeth – Sweating Bullets (Tidal Hi-Fi)
  • Rush’s – Leave That Thing Alone (Flac 16bit/44.1kHz)
  • Slayer – Angel of Death (Spotify)
  • Liquid Tension Experiment 2 – Acid Rain (Spotify)
  • Yosi Horikawa – Bubbles (Spotify)


The Sound:

The FiiO K9 is a powerful desktop type DAC/Amplifier that with an impressive overall sonic performance. The K9 stands out with is dynamism, transparency and resolution, while the general technical capability is extremely good for a device below the 1K price category. What I also really like about the K9 is the very clean, almost pitch black background atmosphere that you can enjoy both with full sized headphones and relative sensitive In-Ear Monitors.

This review has been written after a burn-in period of approx. 100 Hours. I have paired the FiiO K9 with my Asus TUF FX505DU PC. My sound impressions below are mainly based on my experiences over the 4.4mm Balanced output paired with IEM’s like the FiiO FH7S, Meze Audio RAI Penta and Westone Audio MACH60 and with full sized headphones like the FiiO FT3 and HiFiMAN Edition XS.


The FiiO K9 got immediately my attention with its lower frequency response that is produced in a nicely textured, pretty musical and detailed manner. The subbass region is created with a good sense depth and intensity when I do listen to electro and bass guitars or to percussions. The subbass extension and rumble in tracks such as, Daft Punk’s “Doin’ it Right”, Lorde’s “Royals”, Massive Attack’s “Angle” and Armin Van Buuren’s “Vini Vici” was very exciting when I have paired the device with the FiiO FT3 open-back headphone or the Meze Audio RAI Penta In-Ear Monitors.

When it comes to the midbass region I can definitely say that it is produced with mildly amount of coloration that adds instruments nice sense of musicality. The midbass area sounds pretty strong and impactful when I do pair the FiiO K9 with FiiO FT3 Open-Back headphone or the Westone MACH60 and Meze Audio RAI Penta In-Ear Monitor. Instruments like cross drums and trumpets are pretty accented, without to lose the excellent sense of clarity and resolution produced in this area.


The midrange of the FiiO K9 surprised me with its excellent grade of clarity, airiness and resolution. This area is produced with a mildly warm tonality and a pretty natural timbre. Both vocals and a wide range of instruments are shown with a great sense of realism, especially when paired with headphones like the HiFiMAN Edition XS and IEM’s like the Westone Audio MACH60 and the Meze Audio RAI Penta.

The lower midrange of the K9 offers an efficient level of depth and intensity that creates a nice sense of warmth and fullness vocals, especially to male voices such like Isaac Hayes and Dave Gahan. Instruments on the other hand such like an acoustic guitars, violas or trumpets do sound pretty natural and textured, while the sense of clarity and resolution is excellent.

The upper midrange of the FiiO K9 is nicely emphasized that adds the overall midrange presentation a slightly amount of coloration without to be overdone. Instruments like strings, flutes or pianos are reproduced with a decent level of clarity, detail retrieval and extension. Female voices on the hand are shown in a pretty clear and emotional manner, especially headphones such like the FiiO FT3 and HiFiMAN Edition XS do show a very good synergy when paired with the FiiO K9.



The treble range of the FiiO K9 has a pretty natural and dynamic character, which shows a tad of warmth than neutral tonality. It sounds in general pretty controlled and shows an excellent sense of detail retrieval and extension. The transitions from the upper midrange towards the treble region are in general pretty smooth and highly controlled, even while listen to metal music in bad mastered albums like Metallica’s “Death Magnetic”, when paired with IEM’s like the Westone MACH60 and headphones like the FiiO FT3.

The lower treble area is shown with a good sense clarity, presence and definition when I do listen to soprano voices or to instrument like hi-hats or snare drums. Instruments like crash cymbal do sound pretty crisp and detailed. The upper treble region shows excellent grade of resolution and extension, without to have any remarkable sharpness. Instruments such as hi-hats, ride or crash cymbals do sound fairly pronounced, while the sense of intensity and sparkle is on a decent level.

Soundstage & Imaging:

The highly clean and pitch black background of the FiiO K9 creates great conditions for a precise separation and natural placement of instruments and the vocals. The soundstage has a nice holographic atmosphere and a decent sense of depth and wideness. The pretty spacious and airy atmosphere is another highlight of the K9 that I have enjoyed while listen to my music library.



The FiiO K9 is a feature rich All-in One DAC/Amplifier that impressed me with its Power and excellent overall Sonic performance. The K9 borrows some of the critically acclaimed technologies from the K9 PRO/K9 PRO ESS and integrates some new components in order to archive a more affordable price. The final result is a well adjusted Dual ES9068AS DAC chip setup and a fully balanced THX AAA-788+ AMP module design that works perfectly with both sensitive earphones and power hungry headphones. For all these reasons, I definitely recommend the K9 for all audiophiles that do search for a product with a high value for its money.


 Pros & Cons:

  • + Best in Class Sonic Performance
  • + Clean & Powerful Output
  • + Good Hardware Implementation
  • + Synergy with both Earphones/IEM’s and Headphones
  • + Tons of Connectivity Options (Input & Output)
  • + Clean Design
  • + Build Quality
  • + The vertical stand is a nice addition
  • + Excellent Value


  • – No MQA Decoding
  • – A remote controller would be welcome
  • – Fingerprint magnet (it was not easy to take clean photos)


Thank you for the Read!



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