FiiO K9 Pro ESS Review

FiiO K9 Pro ESS

Power

The K9 Pro ESS has the two pieces of THX AAA-788+ modules and they can dish out 2.1 watts of power into 32-ohm load. That’s a serious amount of power and it will have no problems driving any of your cans. On top of that, FiiO ran into a lot of trouble during their R&D phase to lower the output impedance below 1 ohm and they successfully done that. The unit is dead silent regardless of the pairing. My 16 ohm Fostex IEMs are as silent as they get between passages of the tracks and that’s very impressive. 

Technical Capability

The K9 Pro ESS offers excellent PRaT, dynamics and coherency compared to many DACs and AMPs that I have in my arsenal. There is only one thing that puzzles me about the K9 Pro ESS. It does not offer the best soundstage width compared to DACs and AMPs that rivals it. The depth however is quite good and the instruments have ample air between them. For example, the SU-9 & SH-9 stack offers better soundstage but the tonality is nothing alike. The K9 Pro ESS feels much more realistic and organic in comparison. Additionally, the K9 Pro ESS offer a very high level of transparency and an impressive tonal balance across the spectrum. It is a technical marvel minus the soundstage width. Luckily, the unit offers excellent separation and layering. Everything feels neat on the stage, the timbre allows you to focus on the tunes and the immersion is the key. I can’t help my hands during a good drum solo while listening to my favourite tracks via K9 Pro ESS. Musical is what it is, folks.

Wireless Performance

The Qualcomm’s QCC5124 is a reliable and critically acclaimed chipset by many companies around the world. It offers 24-96kHz LDAC streaming and the K9 Pro ESS sounds quite good, wirelessly. It is almost as good as the USB output if you’re just streaming tracks from Tidal. Of course, things change as soon as you launch JRiver and couple of those well-recorded Michael Jackson DSDs. If you’re just a streaming via Tidal or Spotify, I’m sure that you will be very happy with the performance you get out the K9 Pro ESS. The signal stability is brilliant as well, thanks to the long antenna on the back. I can actually force-feed my phone to stream 990 kbps and the signal can get thourgh 3 thick concrete walls. That’s impressive. That antenna IS impressive. If you’re looking for a jack of all trades master of plenty device, this is one with a killer wireless capabilities.

Loxjie D40

Comparisons

vs. Topping E50 & L50 ($500 USD, DAC & AMP Separate Devices)

The E50 & L50 is an award winner stack by Topping and they provided one of the best price to performance ratios out there last year. They are a serious, all work no joke stack that offers a brilliant performance right out of the box. We’ll be comparing two award winning units and clash them together, side by side. Do note that K9 Pro ESS is an all-in-one device unlike the E50 & L50 stack. Okay, first of all, both of the units offer excellent value in their respective price ranges and both of them are great, viable purchases. 

There are a couple of differences between them and I want to start with tonality. The E50 & L50 stack offers a tad more linear, somewhat slightly more artificial approach to sound, compared to the K9 Pro ESS. They do not have the organic and realistic timbre that I liked a lot on the K9 Pro ESS. They feel a tad more aggressive with a sharper bite and a wider soundstage. Apart from that, the bass impact, texture and resolution is better on the K9 Pro ESS. On the other hand, the E50 & L50 stack offer more upper midrange energy and quantity. The K9 Pro ESS’ note weight is thicker and meatier, the instruments have better body and timbre. If your budget is around the 500 mark, the E stack could be an excellent choice.

vs. SMSL D1SE & SP400 ($720 USD & $629 USD, DAC & AMP Separate Devices)

How will the K9 Pro ESS perform against a non-aio DAC & AMP set that costs almost double the price? Let’s find out. Firstly, the D1SE and SP400 are two very well designed products from SMSL. The D1SE is a dedicated DAC equipped with the ES9038PRO chip, just like the K9 Pro ESS, but D1SE utilizes only a single chip, instead of a dual configuration. The SP400, on the other hand, is an HFN recommended amplifier that does its job exceptionally well. Compared to the K9 Pro ESS, this stack feels a tad sharper, more dynamic and slightly more resolving. The stack has slightly better PRaT and much wider soundstage. The difference in technical capability between the products is not as big as you might expect. The law of diminishing returns is at play here. Of course, I should also say that the tonality advantage of the K9 Pro ESS against products up to $1000 mark, is not valid against a high-performance stack like this. If you ask my opinion about the comparison, I’d save some space and money.

vs. Loxjie D40 ($429 USD, All-in-One Device)

First of all, the K9 Pro ESS is powered by dual ES9038 flagship chips and is both heavier and larger than the Loxjie D40. Besides, it has a balanced topology. I tested both products in their ‘best’ condition using the same headset. First of all, the biggest difference I noticed was in the bass presentation. The K9 Pro ESS has a more refined and agile bass compared to the D40. The texture is also better on the K9 Pro ESS as well as the resolution. However, the difference is definitely not night and day.

The D40 performs excellent for its price tag and certainly managed to impress me a lot. Apart from the bass region, the most obvious difference is the difference in the technical capability. The K9 Pro ESS handles congestion-prone tracks with more finesse, manages to salvage as much info as possible whereas the D40 is not as talented in this regard as the FiiO. The K9 Pro ESS has a smoother yet more resolving presentation but it does not have the overly spacious headroom of the D40. The K9 Pro ESS offers a more realistic timbre and organic tonality where D40 feels more linear and flatter. Additionally, the K9 Pro ESS has a very impressive treble presentation with very good resolution and transparency. If you’re on the market for an AIO device and aiming for the $400 mark, Loxjie D40 might be a great option.

Conclusion

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. It is clear that FiiO went through a long and painful R&D process to ensure the success of the device. Every component used has been carefully selected and no expense has been spared. I’m very happy to review this device and if you’re looking for a feature-packed desktop DAC & AMP under the $1000 mark, I highly recommend giving the FiiO K9 Pro a try.

Page 1: FiiO, K9 Pro ESS, Specs & Highlights, Packaging & Accessories, Design & Build

Page 2: Technology & Audio Circuitry, Controls & Operation

Page 3: DAC Performance, DAC-AMP Performance, Low, Mid, High

Page 4: Power, Technical Capability, Comparisons, Conclusion

4.4/5 - (295 votes)
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Long time Tech Enthusiast, an ambitious petrol-head, Yagiz likes his gadgets and always finds new ways into the tinkerer's world. He tries to improve anything and everything he gets his hands onto. Loves an occasional shine on the rocks.

9 Comments

  • Reply April 17, 2022

    James McCook

    Great review thanks.
    Good to know that FiiO is stepping up

  • Reply April 24, 2022

    Israel Silverman

    How does it compare against the AK4499 version?

    • Reply February 2, 2023

      Wojciech Szymański

      which headphone output is the best?

      • Reply February 7, 2023

        Yagiz

        The BAL 4.4mm and XLR 4-pin are the same. They perform superior compared to the UNBAL 3.5mm HPO.

  • Reply July 23, 2022

    Trey

    What are your thoughts when you compare the Shanling EM5 against the Fiio K9 pro ess. they are both the same price and i know you have done a review of both.

    • Reply July 25, 2022

      Yagiz

      I did not review the EM5 therefore I don’t know.
      Thanks.

      • Reply February 10, 2023

        Hans P. Heilmann

        How is Audeze mm50 to listen with Fiio K9 Pro ESS ?

        Thank you for a goid review.

  • Reply February 13, 2023

    james

    Comparison with 400$ range products? i think this dac-amp should be compared with adi-2pro or Dac 3 of benchmark.

  • Reply May 6, 2023

    Fernando Machado

    Hello from Brazil! I’m new to the party, looking for a DAC/headphone amp. Here I found a old Corda Symphony selling for about USD660 and I would like to know how it compares to the new FiiOs! Regards!

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