FiiO K9 Pro DAC/Preamplifier/Headphone Amplifier Reviewed

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The first time I saw a FiiO audio component, the old nursery rhyme “fee, fi, fo, fum, I smell the blood of an Englishman” popped into my head. FiiO’s track record of commandeering the market share of their competitors from England (and elsewhere) due to their high-quality, low-priced offerings renders that rhyme not far off the mark. In recent years, FiiO has continued to produce components that deliver startling performance for a pittance. Their newest and most expensive offering is the FiiO K9 Pro (buy at Amazon for $849). This one combines an audiophile digital-to-analog convertor (DAC), analog stereo preamplifier, and headphone stereo amplifier in one well-proportioned package.  It also looks great, sporting an elegantly simple front panel.

FiiO K9 ESS Pro DAC reviewed
The FiiO K9 ESS Pro DAC is a value player that unlike other audiophile components sits standing up

What Makes the FiiO K9 Pro DAC/Preamp Special?

  • The heart of the K9 Pro is based on two ES9038PRO DAC chips, one dedicated to each channel of audio. With ESS’s latest chipset, the K9 Pro delivers staggering 129 dB signal-to-noise, which puts it into a rarefied category that few other DACs, regardless of price or technology, can match. If you need an extremely quiet DAC, the K9 Pro can deliver an effectively silent background noise level even with the most sensitive speakers or headphones. 
  • The K9 Pro supports a wide variety of digital audio formats, including PCM  from 44.1/16 to 384/32 and quad-rate DSD (aka DSD256). Bluetooth codecs supported via the QUALCOMM QCC5124 chip include SBC, AAC, LDAC, aptX, aptX HD, aptXLL, and aptX Adaptive. It also decodes MQA. You can instantly tell what the current format of your music is by looking at the color of the ring around the large centrally located volume control.
  • The K9 Pro’s headphone output supports both balanced and single-ended connections.The THX AAA-788 headphone amplifier produces a whopping 1100 mW into 300 ohms. The preamplifier section can produce up to fifty-two volts peak for driving power amplifiers or powered loudspeakers.
  • The FiiO K9 Pro even has its own app, FiiO Control, for both Android and iOS. The app lets you control the input, Bluetooth codec, channel balance, volume, and includes multi-band customizable equalization, along with a very complete operating guide. 
  • Audio input options include USB, Toslink, S/PDIF Coaxial, and Bluetooth, as well as single-ended RCA and balanced analog inputs.  
  • Output options include a pair of single-ended RCA as well as balanced XLR outs. 
  • When the FiiO K9 Pro does not have an active source playing, the colored ring around the volume control displays its colors in sequence. If you don’t get sound from the FiiO when you think you should be getting sound, one look at the changing colors lets you know the problem is your source, not the K9 Pro.

Why Should You Care About the FiiO K9 Pro DAC/Preamp/HPA?

Many old-school audiophiles will tell you that chip-based DACs  are less musical in comparison to resistance-ladder or FPGA-based DACs. I would call that blatantly wrong. The K9 Pro combines superb detail combined with a level of timbral balance that challenges DACs that have far higher price tags and exotic pedigrees.

If you don’t want to string a series of boxes together, the FiiO K0 Pro combines three primary functions in one component. All you need to add is a source, and either powered loudspeakers or a power amplifier combined with passive audiophile loudspeakers to complete a system. Unlike many budget components that include similar capabilities, the K9 Pro delivers no-compromise performance from all three of its potential uses.  

FiiO K9 ESS Pro DAC reviewed by Steven Stone
You can place the FiiO K9 ESS Pro DAC more traditionally and it is easier to operate as well as connect

Some Things You Might Not Like About the FiiO K9 Pro DAC/Preamp

  • FiiO recommends placing the K9 vertically for the best air flow and heat dissipation, but when placed vertically it’s hard to read the small print on the front panel. They include a stand to hold it, but I found this as useful as the rubber cover over the balanced XLR headphone output on the front panel, which you must remove to use the connection.
  • The color system that indicates the current source’s bit and sample rates is not terribly intuitive. Unless you have a phenomenal memory, you will have to refer to FiiO’s website or the control app’s guide to figure out what each color means. It took me about a week to memorize all the possibilities. Over time, this obviously gets easier. 
  • The large, centrally located volume control has no clicks or numbers to tell you what the volume level is, only a small dot on the knob itself. It moves smoothly, but makes it virtually impossible to reliably set a reference volume level. The small dot on the control is the only indicator of your output level. 
  • The FiiO K9 Pro does get moderately warm when running. The built-in linear power supply, dual DACs, and six layers of audio processing generate more heat than many three-quarter-sized DAC/ preamps I’ve reviewed. 
  • The K9 Pro does not come with a dedicated remote control. While the app serves as an adequate substitute, it is not as convenient as a physical remote.

Listening to the FiiO K9 Pro…

At the most recent Grammys awards, Bonnie Raitt received the 2023 Song of the Year award for “Just Like That” from her album by the same name. My favorite song on the album is “Blame it On Me.” The interplay between the organ and Ms. Raitt’s killer signature slide guitar slays me every time. The K9 Pro does an exemplary job of preserving all the subtle, low-level background bits. And Raitt’s voice has aged beautifully, a fact the K9 Pro lets you luxuriate in. 

Another winner at the most recent Grammys for Producer of the Year was Jack Antonoff, who records as Bleachers. The line of super-musical nerds in rock and roll goes back as far as Buddy Holly, and Jack Antonoff strikes me as the modern-day equivalent. On his latest album, Live at Electric Lady , every song is beautifully produced. My top track is “How Dare You Want More,” which has not only a rave-up but also a guitar/sax duel. Once more, the FiiO K9 Pro decodes all the musical information in a lucid and euphonic manner. Each instrument in the mix has its own spot, clearly defined in space.

Since we’re on the subject of Grammys, Molly Tuttle’s album Crooked Tree won the 2023 Grammy for Best Bluegrass Album. Qobuz has a deluxe high-resolution 96kHz/24-bit version with some additional live cuts that includes an outstanding cover of Grateful Dead’s “Dire Wolf.” The FiiO gets out of the way of the music the way a good piece of electronics should. On the live version of “Dooley’s Farm,” it’s easy to listen to each instrument in the mix without having to strain. 

Does the FiiO K9 Pro DAC/Preamp/Amp Have Any Resale Value?

Given it capabilities, it’s hard to imagine the FiiO K9 Pro becoming obsolete any time soon. Looking through the Internet, few K9s come up for sale, and those that do go for around 60 to 80 percent of their original retail price. With its excellent specifications and performance, I suspect it will be some time before any company, including FiiO, will produce a DAC/pre/HPA that makes the K9 Pro into an also-ran component. Early signs are good for resale, but we all know the world of digital audio changes quickly as do values of products. 

The FiiO K9 ESS Pro digital to analog converter reviewed by Steven Stone
At $849, the FiiO K9 ESS Pro DAC speaks to audiophiles who are working to build a very high end system but don’t have the all-out budget (yet) but have the tastes for the better things in the hobby.

Who Is the Competition for the FiiO K9 Pro DAC/Preamp/Amp?

The Topping D90SE ($899) has superb overall specifications and has one of the best signal-to-noise figures of any DAC at 134 dB from its balanced output. The D90SE also supports all high-resolution PCM and DSD formats, along with MQA. The D90SE also has the same Bluetooth and preamplifier functions as the K9 Pro, as well as its own dedicated remote. What the Topping lacks is the headphone output and amp of the K9 Pro. If MQA is not your thing, Topping has another version of the D90 called the Topping D90 LE (buy at Amazon) that lacks MQA but otherwise has identical features and performance.

The S.M.S.L. SU-10 ($899) flagship DAC/pre uses the same ESS DAC chips as the FiiO K9 Pro and shares the same PCM, DSD, and MQA decoding capabilities. It also has the extended set of Bluetooth codec options and includes the exact same remote as the Topping D90SE. Its specifications are also equally stellar, but like the Topping it lacks any headphone output options. In comparison to the Topping, the S.M.S.L. offers different ergonomics and display options, so the decision between them could come down to which one’s cosmetics you prefer.

The Cambridge Audio DacMagic 200M ($549 buy at Crutchfield) offers almost the same feature set as the FiiO K9 Pro, including balanced and single-ended analog outputs, high-resolution PCM, DSD, and MQA capabilities, but it lacks balanced headphone connections, isn’t quite as quiet, and its Bluetooth input only supports the aptX and SBC codecs. Also, the 200M uses a pair of ESS ES9028Q chips as opposed to the newer ES9038PRO used in the FiiO K9 Pro.

The FiiO K9 ESS Pro digital to analog converter reviewed by Steven Stone
Here are both standing and laying down configurations of the FiiO K9 ESS Pro DAC

Final Thoughts on the FiiO K9 Pro 

Since I’ve also reviewed the Topping D-90SE at The Absolute Sound, I put together a level-matched blind A/B test of the FiiO K9 Pro versus the Topping D-90SE. After several sessions, I had to admit that I could not reliably tell the difference between the two using a pair of ATC SC7 III loudspeakers driven by the Topping LA-90 power amplifier wired with Audience Au24 SX speaker cables and Kimber KCAG interconnect.

Both the FiiO and the Topping share a similar sonic character, which I would describe as “straight, no chaser.” Neither one will warm up an otherwise harsh recording, and please consider that a very good thing from a modern audiophile perspective. So, if you’re looking for a forgiving or overly euphonic DAC/pre, you need to look elsewhere, like perhaps a tube preamp or a ladder DAC. If you want to get really close to the music with no haze or sonic bloat, either of these DACs will certainly deliver the goods.

Value-wise, since the FiiO K9 Pro includes a good headphone amplifier that can handle even harder-to-drive headphones such as the $3,999 Dan Clark Stealth (buy at Amazon) or much less expensive, $169 Beyer Dynamic DT 990 600 Ohm version, it does deliver more value per dollar than the Topping D90 SE. But if you already have a good headphone amplifier, the headphone functions on the FiiO would be redundant. As a wrote earlier, if you are relying solely on sonics to make your decision between the two, you may find yourself in a dead heat. They are both mighty fine DACs and preamplifiers.

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