FiiO K15 Desktop DAC AMP Review – Brilliance Of The Balanced All-Rounder
FiiO K15 is a $549 USD midrange Desktop Streaming DAC Headphone Amplifier with a Dual AK4497S DAC combo at the heart, a Discrete Class AB Transistor Current Headphone Amplifier, 3000mW + 3000mW Maximum power output and with a fully balanced audio circuit. Today we will review the mighty FiiO K15 and also compare it with other similarly priced DAC AMPs including JDS Labs Element IV (549 USD), Rose Technics RT-5000 (699 USD) and FiiO K17 (899 USD).
Introduction
After the impactful success of FiiO K17, FiiO started working on a more affordable DAC Headphone AMP for desktop, thus coming up with Fiio K15. While the feature list is similar, K15 is much more affordable, but has a similar design as well, so one of the most important comparisons will be between FiiO K15 and FiiO K17, as this has been by far the most requested comparison I have to make to satisfy our readers thirst for knowledge and desire for good music.
As an Amazon Influencer, I earn from qualifying purchases, and using the purchase links in my reviews helps me maintain this website and Youtube Channel. Huge thanks to FiiO for providing us with the sample for this review.
Product Link
Amazon – https://amzn.to/41SSM6E
Aliexpress – https://s.click.aliexpress.com/e/_o2FasOT
Build Quality – Design
FiiO K15 is at least on paper just as impressive as FiiO K17, coming with a Dual AKM DAC combo at the heart, having an AK4497S x 2 setup, which is the first time featured in any product we review as of today. The closest we’ve seen is a Dual AK4497EQ which has been featured in multiple products including FiiO M11 PRO, Singxer SDA-2, Astell&Kern A&Futura SE180. Furthermore, the full name of this DAC is AK4479SVQ, which includes the upgraded Velvet Sound developed by AKM Asahi Kasei.
For the headphone amplifier part, we have a discrete headphone amplifier circuit featuring an OP-Transistor current boosting design. A complementary pair of the ON Semiconductor MJE243G / 253G delivers high current and a low impedance combo. This whole headphone amp can produce a balanced output of up to 3000mW + 3000mW in balanced mode.
USB DAC – through the XMPS 16-Core XU316 heart, with support for up to 768 kHz / 32 Bit, DSD512
Bluetooth decoder – supporting SBC, AAC and LDAC
Coaxial Decoding through the optical input
Coaxial Decoding for the Coax RCA input
Single Ended Line input and Output, allowing K15 to be a headphone AMP, or DAC for an external system
Balanced Line out – using XLR balanced outputs
Streamer, using Roon Ready and AirPlay
Local USB Playback from an external storage
Each circuit board is separate, so you have the internal power supply digital and analog boards on separate physical cards, and K15 has a DC/AC 30W 12V – 2.5A low-noise, high efficiency power supply. K15 also supports external DC power supplies, if you have a high-end linear power supply for it.
For a stable performance, FiiO K15 uses a Dual Master Core with X2000 at the heart, this CPU having dual Xburst@2 core + Xburst@0 micro core, An efficient MCU ESP32-23 integrated Xtensa 32-Bit LX7 Dual Core coprocessor allows for precise system control. I almost always forget that the display is touch based and it is how you’re supposed to use most features, but FiiO also has a 10-Band high-Precision PEQ that works on USB, coaxial Optical, bluetooth Streaming and Local Playback. You don’t even need to install any software and this one can be used from the web based PEQ configurator. Wifi is provided by a Gigabit Ethernet port, with an AP6256 Wifi module that supports 2.4 GHz and 5.0GHz.
USB DAC – Subjective Usage
Even though K17 and K15 are made on the same idea, K15 is tighter, each button clicks more nicely, feels better made. K17 is a bit more loose, less clicky, but overall K15 feels crisp. Display brightness, everything else is the same.
USB DAC function is flawless, no DAC delay, and most other functions are the same, but K15 gave me a scare, I did not check and it was set to receive power via DC, a situation in which it does not see the AC cable connected, and it will not start. It is important to make sure that it is set correctly for the power input.
Most functions are exactly the same as those of FiiO K17, there is very little difference, and it would be better to read the review for K17, rather than expand here, as it would mostly be copy paste from it.
Sound Quality
Pairings – I have paired the new FiiO K15 with a selection of earphones and headphones including KBEar Cepheus, Crosszone CZ-10 Enhanced, NFAudio NE4, NfAudio NA2+, Rose Technics QT-X, Palma DHS-1, Audeze MM-100, HIFIMAN Shangri-La Electrostatic System, Kiwi Ears Atheia, FiiO FT7, ZiiGaat Luna, Erzetich Thalia, Erzetich Mania 2024, Moritz Audio Enzo, HIFIMAN Susvara Unveiled, Dunu Vulkan 2, Sivga Peng, HarmonicDyne Baroque, Mrotiz Dragon, Sivga AIVA 2, Soundz Flame, YanYin Canon, and RAPTGO LEAF D01.
It has more than enough power for most casual headphones like HIFIMAN Sundara, HIFIMAN Arya Organic and even Susvara Unveiled. In fact, in terms of raw volume, it is similar to K17, gets loud and fast, but has a bit less control, so it is better for easier to drive headphones. With IEMS, it does not have a noticeable noise floor, it is quite convenient to listen to. Loudness saturation gradient is different and so is the voltage power curve, so with K15, it is easier and recommended to just set the gain to the lowest setting that gives enough volume, as it saturates the power better relative to the voltage.
Overall Signature – FiiO K15 has a more commercial sound than K17, it has a natural, clean, enjoyable sound, but with less dynamic Oomph, it works a bit better for commercial, new and dynamically compressed music, has a bit more transparency, as K15 is rather flat and direct, neutral. K15 is great for versatility, it won’t wrong any music style, will sound accurate and straight to the point with all music. It is quite a bit more revealing than the Chifi competition like SMSL DO400 and such.
Bass – Low-end is likely the most transparent and flattest point of K15, which I was expecting to be warmer considering my experience with FiiO K15 which is a fairly impactful bass. K15 goes for the highest transparency and cleanest delivery possible, it is technical, fast, snappy and precise in the bass, has less depth, and because it has a lower driving power than K17, you will hear a straight-to-the-point sound with all headphones. With a fast decay, K15 sounds more technical and studio-like making the big brother sound audiophile, slower and more bloomy.
Midrange – In the voice we trust, and FiiO K15 is transparent, brings forward voices and instrumental layers, it is direct and clean, crisp, and fast. This results in a highly analytical and revealing sound with a strong lateral separation and layering, very good female and male voicing, but a slightly vocal presentation. It is strongly revealing of details in the midrange where most information in music happens, but this makes it quite flat and neutral and compresses the dynamic range slightly.
Treble – At the top end, FiiO K15 is rather smooth, silky and lush, it takes away edge from music, even technical death metal can be listened to with a brighter pair of headphones making it an excellent companion for the usual suspects, like planar magnetic headphones. This makes it less faithful to the original recording, which is interesting, as this is the only way it breaks from being sharp, analytical, fast and neutral.
Dynamic Range And Textures – FiiO K15 has a slight dynamic compression factor, it brings forward details from the background, has a slightly compressy sound, this works very well for modern and new music. Textures are very detailed, sharp and a bit dry in the bass and midrange, it feels really technical and crisp, but in the treble it is smoother and more relaxed, more refined and silky. This type of sound is ideal for rock, metal, EDM and Pop, and less ideal for classical, and acoustic music.
Loudness Saturation Gradient – FiiO K 15 saturates the volume better on lower gain levels, it is best to keep it on the lowest gain level that allows you to enjoy music with volume set towards max, on low gain. This way it delivers the highest current and power for the voltage, resulting in more oomph, more impact and a higher bass impact at a lower THD, less dynamic compression, which happens on very high gain levels.
Soundstage – FiiO gave K15 a rather wide and holographic sound, it has excellent lateral dispersion, but tends to have less depth, especially as it has a limited bass depth and warmth, so you can expect sound to be wide and airy, impressive in instrument separation, but with a natural depth. It provides excellent separation between the foreground and background layers.
Comparisons
FiiO K15 vs JDS Labs Element IV (549 USD vs 549 USD) – From a built perspective, Element 4 is a far more compact DAC AMP for the same money, it only has RCA outputs, but still with a fully silent background, so no disadvantage compared to the XLR line out of K15. Element 4 has a far more advanced EQ, it can do more tweaking, but K15 is much simpler to use and to get good results out of. K15 has fully balanced headphone outputs, Element 4 has only SE outputs (cables, connectors, other considerations). Element Iv has the power converter with a long cable, K15 can use any cattle plug cable that can be as long as you desire. Element Iv is mode futuristic, K15 is more retro.
Sonically, Element Iv is the most direct competitor, but sounds more organic, richer, a bit warmer and with a bit more impact, but at the cost of having a slightly more compressed sound than K15. While both are quite revealing, Element IV delivers slightly more detail from the background, while K15 allows for a wider, more holographic sound. Element IV has a deeper, more layered sound, K15 is flatter, but more holographic laterally. Both are very interesting, I prefer K15 for modern music, Element Iv delivers a richer sound for classical music and acoustic music.
FiiO K15 vs Rose Technics RT-5000 (549 USD vs 699 USD) – In build, both are retro devices, both have XLR Line outs, but while K15 has EQ, RT-5000 comes already with a certain smooth – warm – sweet coloration in the sound, one that is there for both the headphone output and line out. For hard to drive headphones, K15 has more power, while for IEMS, K15 has a lower noise. If you’re into artsy products, RT-5000 looks far more artsy, while K15 looks retro-industrial, taking inspiration from the British Industrial Revolution, while RT-5000 looks like a valuable Antiquity.
Sonically, RT5K is very warm, colored, while K 15 is far more neutral, flatter, more dynamically compressed and less colored than RT5000. If you want a DAC Headphone AMP that will heavily change the signature of your setup like RT-5000, then it will have that colored sound for both the line out and the headphone output, while FiiO K15 has a strongly neutral sound for both the headphone output and the line out. K15 is more detailed and more crisp, but FiiO K15 has a stronger impact, bass that reaches lower, and has more impact, smoother treble with less edge to it. K15 is most definitely more transparent while RT5K has a pleasing coloration.
FiiO K15 vs FiiO K17 (549 USD vs 899 USD) – In the build, K17 looks a bit larger, but when I placed them on top of each other, they are literally the same size, same outputs, same buttons, same display, same feature set, but K15 has a lower maximum driving power, lower power needs, can be powered via DC input, and both have a powerful EQ that you can engage easily. Basically, externally they are the same DAC AMP, with very similar functions.
Sonically, FiiO K17 has a higher dynamic range, better detail revealing ability, much better resolution, stronger impact and headphone driving ability. This being said, K15 is a bit more processed, it brings forward details nicely in commercial and modern music, it is great for someone who wants to hear it all and mostly listens to EDM, Rock, Metal and new music. K15 is still excellent and its price range, it is very easy to recommend, there’s almost a 2X factor in the price difference and K15 is most certainly more than 90% of what K17 can deliver sonically, and 100% of the technical ability and performance in software and features, so don’t look down on it, K17 will be better for sure but K15 has a stronger price performance ratio.
Value and Conclusion
With a price tag of less than 600 USD, and little bit above half of FiiO K17, FiiO K15 has one of the strongest price / performance ratio factors in the whole world, it is a direct competitor to JDS Labs Element IV, but with more power, XLR Preamp outputs, and more driving power too. FiiO has a less complex EQ, but for most headphones I discourage users from EQ’ing anyways, as it comes with its own drawbacks like introducing changes in phase and delay.
At the end of the day, FiiO K15 is brilliant, it sounds natural, clean, enjoyable, organic and musical with a safer, more processed tuning, which works even better for commercial music but also can be enjoyed with Jazz. While not quite at the same dynamic range of K17, FiiO K15 is affordable and if you’re around 500 USD, it is one of the best desktop DAC AMPs you can grab, especially if you’ll be using both headphones and speakers, it has very nice RCA, XLR preamp outputs and an excellent headphone amplifier too with an enjoyable and musical DAC.
PROs
- A set of features as complete and versatile as FiiO K17
- Outstanding driving power at maximum
- Streaming, ethernet, Fully balanced design, XLR Line Outs, versatile usage
- Clean and beautiful design
- DC input for a Linear Power Supply
- Touch screen controls
- Web EQ that is just as versatile but much simpler to use than the one JDS Element IV
- Natural and clean sound
- Very enjoyable and a bit processed
- Slightly dynamically compressed, draws details more to the foreground making small bits of information very easy to hear
Cons
- Gets warm during usage
- The idea that the display is touch screen is something I forget EVERY SINGLE DAY
- Existence of K17 which I prefer makes K15 ever so slightly underwhelming if you have the money for the big brother
Product Link
Amazon – https://amzn.to/41SSM6E
Aliexpress – https://s.click.aliexpress.com/e/_o2FasOT
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Full Playlist used for this review
We listened to more songs than those named in this playlist, but those are excellent for identifying a sonic signature. I recommend trying most of the songs from this playlist, especially if you’re searching for new music! The playlists are different for Spotify, Tidal and Youtube, and based on the songs I enjoy and are available on each!
https://www.youtube.com/playlist?list=PL_cjBXGmwSHSdGcwuc_bKbBDGHL4QvYBu
https://open.spotify.com/playlist/5J3oloz8Riy9LxEGenOjQ0?si=979ba4f082414be7
https://tidal.com/browse/playlist/330fd544-8e5b-4839-bd35-676b2edbb3d5
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