Fiio K9 Pro ESS review: An outstanding high-end desktop DAC/amp

With a clean sound and extensive connectivity options, the K9 Pro ESS is worthy of an end-game DAC.

Fiio K9 Pro ESS
(Image: © Harish Jonnalagadda / Android Central)

Android Central Verdict

The Fiio K9 Pro ESS is a fantastic all-in-one DAC/amp that delivers a transparent sound, allowing your headphones and IEMs to shine. It comes with extensive connectivity options that include Bluetooth 5.0 and wireless AptX codecs. The caliber of hardware combined with the design and audio quality make the K9 Pro among the best desktop DACs you can buy for under $1,000.

Pros

  • +

    Excellent all-in-one DAC/amp

  • +

    Clean and balanced sound with no distortion

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    Plenty of power to drive demanding headphones

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    Bluetooth 5.0 with high-fidelity audio codecs

  • +

    384kHz/32-bit PCM, DSD256, and 8x MQA decoding

  • +

    Robust build quality

Cons

  • -

    No integrated screen

  • -

    Misses out on DSD512/16x MQA decoding

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Fiio is a brand that needs no introduction; the Chinese audio manufacturer is well-known for its budget DACs and IEMs, and over the last 18 months it has branched out into new product categories and set its sights on the mid-tier and high-end segments. The result is the K9 Pro, a flagship desktop DAC/amp that delivers an incredible set of features. It has dual ESS ES9038PRO DACs, a 6.35mm port alongside balanced 4-pin XLR and 4.4mm ports, MQA and DSD decoding, Bluetooth 5.1 connectivity with high-res wireless codecs, and a custom stand that lets you mount the unit vertically.

In short, you're getting all the features you could ask for in a high-end DAC/amp, and that's a good thing considering the K9 Pro costs $849. For context, that's nearly six times costlier than the K5 Pro. The K9 Pro has much better internals — the DACs in use are the same as the M17 music player, and that retails for $1,700 — and you get an elegant design that looks great on your desk. Furthermore, the sheer number of features on offer make it a great option as an end-game DAC.

I've used the Fiio K9 Pro for over three months now, and here's why I think this is the ultimate all-in-one choice if you want a high-end DAC/amp for use with headphones.

Fiio K9 Pro ESS: Pricing and availability

Fiio K9 Pro ESS review

(Image credit: Harish Jonnalagadda / Android Central)

Fiio unveiled the K9 Pro in Q4 2021, with the first iteration of the product coming with AKM DACs. But given the shortage of the same, Fiio pivoted to ESS, relaunching the K9 Pro at the start of 2022 with the ESS ES9038PRO instead. The AKM version was initially available for $699, but you can't get your hands on that model and will need to go with the ESS variant if you're eyeing this DAC.

The ESS version of the K9 Pro costs $849 on Amazon (opens in new tab) and Fiio's website, and you can get your hands on the DAC at major audio retailers globally. As is the case with other Fiio DACs, you get a standard two-year warranty.

Fiio K9 Pro ESS: Design

Fiio K9 Pro ESS review

(Image credit: Harish Jonnalagadda / Android Central)

Fiio isn't known for its flashy designs, with the brand instead delivering products with a clean aesthetic that looks good on your desk. That's what you get with the K9 Pro as well; the design doesn't stand out too much, but it is immediately evident that this is a high-end product. There's a Pro label prominently visible to the left, and the large volume knob decked out in gold and an RGB LED ring encircling it give K9 Pro a little more panache on the styling front.

The black anodized aluminum design makes the DAC look that much more elegant, and while the overall design is more rectangular than the K5 Pro, the beveled edges at the front make the unit feel less boxy. With dimensions of 200 x 224.5 x 72mm and a weight of 6lb (2.7kg), the K9 Pro has a reassuring heft to it. There are vents on either side of the unit for managing heat, and they do a decent enough job ensuring the K9 Pro doesn't get too hot.

Coming to the connectors, you'll find a single-ended 6.35mm port at the front along with a 4-pin balanced XLR port and a 4.4mm balanced port. To the right of the front panel, you'll find status indicators that highlight the connection mode that's currently active. There are four buttons to the bottom of the right that let you power the unit on or off, changing the gain levels, switch sources, and select what configuration to use the K9 Pro in: a DAC, preamp, or DAC/amp.

Fiio K9 Pro ESS review

(Image credit: Harish Jonnalagadda / Android Central)

At the back, you'll find an exhaustive list of inputs that include both digital and analog. On the digital front, you get USB, Bluetooth, coaxial, and optical. As for analog, there's RCA and 4.4mm line in as well as RCA out and a balanced 3-pin XLR out. Fiio hasn't left anything out here, and you also get a USB-C port on the right side of the unit that makes it straightforward to connect a mobile source.

Fiio K9 Pro ESS review

(Image credit: Harish Jonnalagadda / Android Central)

The build quality itself is phenomenal, and there are zero issues in this area. The clean lines combined with the metal chassis make the K9 Pro look unmistakably premium, and you get all the connectivity options you want. My only quibble in this area is that the labels for the buttons at the front aren't visible against the design, and I had to use the flashlight on my phone for making any changes. While the design has a matte finish, the volume knob has a glossy coat and picks up smudges fairly easily. Other than that, it has been smooth sailing with the K9 Pro.

Fiio K9 Pro ESS: Features

Fiio K9 Pro ESS review

(Image credit: Harish Jonnalagadda / Android Central)

Fiio bundles the K9 Pro in a large box that contains the DAC along with a host of accessories. You get rubber feet, USB-A to USB-B cable, 3.5mm to 6.35mm connector, a custom stand that lets you mount the unit vertically — to free up room on your desk — and a Bluetooth antenna that affixes at the back. 

The first thing you do after unboxing the K9 Pro is select the voltage; there's a switch located on the underside of the unit that lets you change between 115V and 230V, and you need to set it accordingly for your region. I'm using the DAC in India, and the unit was set to 230V out of the box, so I didn't see any need to change it.

Fiio K9 Pro ESS review

(Image credit: Harish Jonnalagadda / Android Central)

Coming to the audio hardware, the K9 Pro features flagship-tier ESS Sabre Pro ES9038PRO DACs, and they're used in a dual-channel configuration. There are two THX AAA 788+ linear amplifiers that have been customized for the K9 Pro, the standard 788 module was prone to overheating with continuous use, so Fiio worked with THX over the 788+ to deliver better heat dissipation and more output power.

On the wireless front, you get Qualcomm's QCC5124 audio SoC that enables Bluetooth 5.0 and comes with a host of wireless codecs, including AptX HD, AptX LL, and LDAC. Switching to wireless mode is effortlessly easy, and I didn't have any issues connecting to the DAC via the best Android phones. Thanks to the antenna boosting the range, I had zero issues with connectivity or range, with the DAC staying connected to my Pixel 7 Pro over 30 feet away.