Home Amps/DACS FiiO K9 Review: A Better Value Than The Pro Version?

FiiO K9 Review: A Better Value Than The Pro Version?

by Stuart Charles Black
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Greetings mate and Welcome aboard!

Stuart Charles here, HomeStudioBasics.com helping YOU make sound decisions, so…

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FiiO’s flagship K9 has gone through quite a few iterations in the last several years.

If you’ll recall, I initially covered the AKM version with the ESS not too far behind. 

The K9 we’ll discuss today isn’t a “Pro” model but still functions like one and it’s a few hundred dollars cheaper.

And because I’m a value whore, I think the K9 could be a better overall purchase.

But is it?

Let’s get into specifics and find out.

The K9, like the others, is built incredibly well. It’s large and in charge like Ms. Puff, (AKA DUMMY THICC) but doesn’t feel overly bulky.

FiiO gives you the option to lay it flat or on its side with the inclusion of a padded stand. Neato.

Speaking of accessories, the K9 comes with the unit, 1x Power Cord, 1x Headphone Plug Adapter, 1x USB Data Cable, 6x Feet pads, 1x Fuse, 1x Stand, A Quick Start Guide, Voltage Selection Card, and a Warranty Card.

For comprehensive specs, click here.

General Specs

  • DAC: ES9068AS*2
  • Decoding Chip: XMOS XUF 208
  • Amplifier: Dual THX AAA 788+
  • Bluetooth Chip: QCC5124, Bluetooth 5.1
  • Bluetooth Format Support: LDAC/aptX 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 (32Ω balanced/THD+N<1%)
  • Output Power 2: L+R≥780mW(300Ω balanced/THD+N<1%)
  • SNR: ≥124dB (A-Weighted, UAC)
  • Noise Floor: PO < 4.8µV (A-Weighted); BAL <9.3µV (A-Weighted, UAC)
  • Output Impedance: <1Ω (32Ω load)
  • Weight: About 2660g
  • Dimensions: 200×224.5x72mm (excluding feet)

What Is It?

Like the others before it, the K9 is an Amplifier + DAC rolled into one and will primarily act as your desktop solution for general headphone and/or speaker/monitor listening.

In addition to its ES9068AS chip, it’s a powerful unit and boasts 780mW into 300Ω.

I can assure you this is roughly 555x more than you’ll ever need, but recently, the trend in DACS has shifted from companies providing more than enough power, to crybabies demanding even more because “they’re the customer.”

No seriously, John Seaber over at JDS labs told me that someone actually said “It’s not a matter of do I need it, but more so, because I want it.”

To those people, I say, you’re a bad egg like Veruca Salt and should be dealt with accordingly – because this is how you sound:


Before I go off on a rant, I’ll just say the K9 has plenty of power and with a low output impedance, you can rest assured knowing your listening experience will be everything you ever dreamed of and then some.


As with all FiiO products, the build here is impeccable and a testament to the company’s staying power.

I’ve been demoing their stuff since 2018 and haven’t once had anything break down on me. Occasionally you’ll need to do a hard reset, but even that’s rare and I’ve only had to do it a couple of times with other dacs.

As jaded as I am about gear nowadays, I still look forward to holding a FiiO DAC in my hand. It just feels so good, man.

I’ve even taken one to bed for a special occasion like Smokey Robinson.

Haha just kidding. Or am I?

The unit itself is all aluminum CNC configuration; a process utilized for precision machining of casings or chassis components.

CNC machines carve out intricate designs from materials like aluminum or steel based on digital designs or blueprints, ensuring accurate dimensions and smooth finishes.

This method allows for high-quality construction of DAC enclosures with precise alignment of internal components, contributing to overall performance and durability.

And when you put one in your hands, wait for it…


Front Panel

FiiO K9 Review

The front contains 3 headphone outputs: a balanced XLR-4, balanced 4.4mm, and single-ended 1/4″ (6.35mm).

Next to that is the Volume Knob, powered by ADC curve reconstruction allowing you to precisely and smoothly adjust through 120 levels of volume.

FiiO K9 Review

No noise, no distortion, and volume matches on the right and left channels for your aural pleasure.

The DAC also gradually raises the volume when you press play; a lifesaver for your ears if you were listening to super inefficient headphones and forgot to turn it down before switching to a more efficient set.

ADC Curve Reconstruction

ADC curve reconstruction in a DAC refers to the process of converting a digital audio signal back into its analog form using interpolation techniques.

This involves reconstructing the original analog waveform from discrete digital samples obtained during the analog-to-digital conversion (ADC) process.

The DAC utilizes algorithms to smooth out the digital steps and recreate a continuous analog signal, aiming to minimize distortion and accurately reproduce the original audio waveform with fidelity and precision.

The knob is also backlit with RBG lights that change according to sample rate and Bluetooth format:

  • Blue = 48kHz or below
  • Yellow = Above 48kHz
  • Green = DSD

Bluetooth Formats

  • Blue = SBC
  • Cyan: AAC
  • White: LDAC
  • Yellow: aptX HD
  • Magenta: aptX/aptX LL
  • Green: aptX Adaptive

The colors also cycle through in a rainbow configuration. In other words, it’s super gay but hey, being fruity is all the rage nowadays.

Next to the Volume Pot are your input signals: USB, Optical, Coaxial, LINE, and Bluetooth. Just press the input button to cycle through.

FiiO K9 Review

FiiO K9 Review

Line mode includes an RCA and 4.4mm input. If both are connected, the 4.4mm input is prioritized.

Below the input signals are the output switch, gain switch, input button, and the mute/power button.

Long-press to power on/off, short press to mute/unmute.

FiiO K9 Review


  • LO: Rear RCA/XLR analog outputs are active, at max output and cannot be adjusted by the volume knob.
  • PRE: Rear RCA+XLR analog outputs are active, and can be adjusted by the volume knob.
  • PO: Only the front headphone outputs are active, and can be adjusted by the volume knob.

Back Panel

FiiO K9 Review

FiiO products provide great value due to the amount of options you have. With the K9, you can hook up to almost anything in a home studio/theater space.

With its coaxial input, you’re able to connect to things like TVs, CD Players, and generally anything that outputs coax. The optical input is great for console gaming with my PS4 and even works with my older Playstation 3.

With its RCA outputs, you can use the K9 as a preamp into separate speakers like the Presonus Eris e3.5, or hook up to a separate headphone amplifier of your choosing.

The 4.4mm input allows you to connect to another DAC that has a balanced output(s).

The RCA inputs allow you to use a separate DAC, and you even have the option of connecting a turntable as long as it has RCA males. A lot of USB turntables like my Audio Technica AT-LP60 are great for listening to vinyl with the K9.

Lastly, the balanced XLR outputs are great for use with studio monitors like the Yamaha HS7 – or anything that utilizes TRS or XLR inputs. 

FiiO goes the extra mile by providing the unit with Bluetooth capability; this time with a built-in antenna vs. the screw-ons of the past.


Truly Balanced Design

A truly balanced design in DACs involves the implementation of a symmetrical circuit architecture where both the positive and negative halves of the audio signal are processed independently and with equal impedance throughout the signal path.

This design aims to minimize noise and interference while maximizing signal integrity and dynamic range.

Dual-mode clock management

Dual-mode clock management in DACs refers to a capability where the device operates in two distinct clocking modes: synchronous and asynchronous.

In synchronous mode, the DAC synchronizes its output with an external clock signal, ensuring precise timing and reduced jitter.

In asynchronous mode, the DAC generates its own clock signal internally, allowing for greater flexibility and independence from external timing sources.

This dual-mode functionality enables the DAC to adapt to various system configurations and performance requirements effectively.

THX AAA 788+ amplifier

FiiO K9 Review

A THX AAA amplifier is a high-fidelity audio amplifier technology developed by THX Ltd. It stands for “Achromatic Audio Amplifier” and is designed to deliver exceptionally low distortion and noise, offering an audiophile-grade listening experience.

THX AAA amplifiers utilize patented feed-forward error correction technology to minimize harmonic, intermodulation, and crossover distortion, resulting in transparent and accurate sound reproduction.

They are prized for their ability to maintain audio fidelity across a wide range of load conditions, making them suitable for demanding audio applications and critical listening environments.

Do I believe it makes a marked difference?

For that, click here.

Dual-voltage linear transformer

A dual-voltage linear transformer in DACs refers to a power supply mechanism that provides two separate voltage outputs for analog and digital circuitry within the DAC.

This design helps isolate the analog and digital components, minimizing interference and noise in the audio signal path.

By supplying clean and stable power to both sections of the DAC, the dual voltage linear transformer enhances the overall performance and fidelity of the audio output, resulting in clearer sound reproduction and improved signal-to-noise ratio.

For an exhaustive list of more features, click here.

As for my opinion? I do think any measure taken to improve the signal-to-noise ratio is likely the most important aspect of a DAC – this according to the SINAD standard of > 90dB.

For that, I appreciate that FiiO attempts to improve these factors in their DACS, but I will also say that none of them are the end all be all and your perception of those improvements can be limited to almost non-existent.

Intelligent Protection Systems

The K9 includes 3 of them – preventing overheating, overload, and DC protection for a worry-free experience.

FiiO Control App

FiiO K9 Review

I have to say the app is still a bit clunky, but I was able to get it going after a few roadblocks.

For instance, it’s trying to upgrade the firmware but won’t finish and gets stuck in a loading loop. In other words, it froze and I couldn’t exit the menu.

After rebooting and trying again, it eventually finished and I was able to use it.

All things considered, I think the App is a pretty good add-on, but you may run into some minor headaches along the way.

With it, you can adjust various settings including filters, status indicators, EQ, and channel balance.

Click below to scroll through some images of the App:


FiiO K9 Review

Hm.. How do I succinctly sum this up without going on another rant?

The DAC does its job. How about that? It provides a clean digital-to-analog conversion, has a low output impedance, and is more powerful than explosive diarrhea.

Any more questions?

With the control app mentioned above, you can use its PEQ (Parametric Equalizer) to adjust the sound, or use one of their 7 presets.

K9 vs. K9 Pro

Both have ESS chips, but the K9 Pro’s is a 9038 vs. the K9’s 9068. The K9 is lighter at 2660g, doesn’t have a Type-C port, has 3 filters vs. 7, and has the PEQ feature. The K9 Pro ESS doesn’t.

The K9 doesn’t have an MQA renderer, so if you’re looking for that, you may go with the K9 Pro or something cheaper like the K7.

The K9 supports up to 768kHz/32-Bit, and DSD512, while the K9 Pro supports 384kHz/32-Bit/DSD256.

The K9 Pro’s signal-to-noise ratio is a bit better: 129dB vs. 124.

Final Verdict

FiiO K9 Review

If you’re familiar with this blog, you’ll know I recommend DACs based on value – not “sound.” 

The K9 at $499 (Subject to change) is an excellent purchase and likely the best all-in-one desktop end-game solution you could ask for at this price point.

It will certainly replace my K9 Pro all-in-one recommendation based on $$$ alone.

FiiO is one of the few companies that understand the ultimate value of a product (i.e. what it’s truly worth) and thus why I recommend them so often.

The K9 is simply a more sensible option and appeals to a larger demographic of people. I thought the original AKM at $699 was worth it, and the K9 at $499 just makes the decision easier.

So, if you’re looking for that all-in-one and want to splurge a little without burning a hole in your pocket like some elitist audiophile weirdo, the K9 (non-pro), in my opinion, is the best option until something better comes along or FiiO adjusts their prices.

Given the K9, from a technical standpoint, is equal in most regards to the “Pro” version (and even improves in other ways), it seems strange that it’s priced much lower.

But hey, that’s good news for you and me, as it basically means we won’t be whoring ourselves on local street corners for more money to support our grotesque DAC habit:

And I’m out.


Well, that’s about it for today my friend! I hope you’ve enjoyed this FiiO K9 Review.

Questions? Comments? Requests? Did I miss the mark on something? Let me know down below (please keep it civil) or Contact me!!

If you love what I do here and want to support the blog and channel in a more personal way, check me out on Patreon and discover all the value I have to offer you.

Is the K9 worth a purchase? I would love to hear from you. Until next time…

All the best and God bless,





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