FiiO K7

Specifications:
Model : K7
DAC : AK4493SEQ x2
Decoder : XMOS XUF 208
Amplifier : Dual THX AAA 788+
Volume Chips : NJU72315+OP
Outputs : 6.35mm Single-Ended + 4.4mm Balanced
Inputs : USB, Optical, Coaxial, RCA
6.35mm SE Output : up to 1220mW @ 32Ω / 140mW @ 300Ω
4.4mm BAL Output : up to 2000mW @ 32Ω / 560mW @ 300Ω
SNR : >120dB (A-weighted, UAC)
Noise floor : PO<4.1uV
THD+N : ＜0.0003% (1 kHz/32Ω/dbA)
Output impedance : <1Ω
Dimensions : 120 x 168 x 55mm
Weight : 610g

Inside the box :
1 x FiiO K7 Desktop Headphone DAC/Amplifier
1 x USB-A to USB-B cable
1 x Power Cable
1 x Power Adapter
1 x User Manual & Warranty card

The Fiio K7 is an all-in-one unit that sells for under $200. It features a Full Balanced HiFi DAC Headphone Amplifier AK4493S*2, XMOS XU208 PCM384kHz DSD256,USB/Optical/Coaxial/RCA Inputs, 6.35mm/4.4mm Outputs.

About the Fiio K7
The most competitive and cost-effective desktop balanced DAC/Amp within the 300-USD range.
Adopts the six-stage audio circuit as in FiiO’s high-end devices and features 2 AMK’s latest AK4493SEQ DACs and dual THX AAA 788+ amps.
Supports multiple outputs- 4.4mm balanced out, 6.35/3.5mm single-ended out, as well as multiple inputs- USB, optical, coaxial and AUX in.
Comes with versatile functions as well as robust output power- 1% THD+N under BAL output, 2000mW stable output power, which can drive most headphones, including full-size headphones.
Supports input selections, 2 gain levels and 3 output levels, and features RGB indicator lights that can display the working state and differentiate sampling rates.

Sound:
The Fiio K7 is clear and natural sounding with low noise and a hint of warmth to give it character. It is decently transparent, detailed and open sounding with great dynamics.
Performance:
The device performed well with full-sized Planar headphones and sensitive hybrid IEMs. All BA IEM however there was a slight hiss at start, but this dissipated with music.
Gear used:
AKG 712, and K240
HIFIMan Ananda, HE x-4 and HE350
Kinera Hodur, Celest pandamon, and Sif
Hidizs MS5 and MD4
KZ Krilla, AS24, and CCA Duo

Over the past few months, you have seen FiiO K7 as the reference DAC/amp to review other IEMs and earphones. It is finally time for the K7 to get on my review table for dissection.

Let’s discuss FiiO K7 and whether an IEM listener should / should not get a desktop DAC/amp such as K7.

Preambles:​

• I use the term “source” to denote a DAC + Amp combo.
• Sources do not make sounds. Therefore, when I say sources “sound” a certain way, I talk about the change they make to my IEMs and earphones.
• I want my music to be crisp, clear, well-separated and form a 3D soundstage around my head. Sources that intensify those characteristics of my IEMs are considered “better”.
• Ratings are given based on A/B tests with benchmark sources and IEMs.
• Making loud noises does not mean that a pair of IEMs or earphones are driven to their full potential.
• Despite my textual descriptions, improvements from sources are minor and nuanced. If you are beginning your head-fi journey, getting different IEMs or earphones would yield more benefits. If you know your gears very well, source improvements can be delightful.
• The K7 used for this review was a sample provided by FiiO (Thank you!). The unit is retailed for USD $200 (AUD $340). Australians can buy the K7 from the official retailers Addicted to Audio and Minidics. Folks elsewhere can refer to FiiO retailers list.

Specs:​

• DAC Chips: AK4493SEQ x2
• Amplifiers: THX AAA 788+ x2
• Output ports: 6.35mm (Single-ended) and 4.4mm (balanced)
• Input ports: USB-B (data), RCA inputs, optical, coaxial
• Single-ended output power: 1220mW@32ohm per channel, THD+N < 1%
• Balanced output power: 2000mW@32ohm per channel, THD+N
• Output impedance: < 1ohm (32ohm load)
• MQA support: N/A

Non-sound Aspects​

K7 comes in a large box with the familiar sci-fi design motif and holographic prints. Inside the box, you find the K7 itself, a USB-B to USB-A cable, a 6.35mm to 3.5mm adapter, a big power brick, and the K7 itself.



So what exactly is K7?

It’s an all-in-one unit with Digital-Analogue-Converter (DAC) and headphone amplifier. You can use K7 like a USB DAC/amp dongle: USB side to the laptop, audio side to your favourite headphones or IEMs. Noted that you need to plug the K7 into wall power.

Moreover, K7 would take over all audio output duties and disable the volume control feature on your laptop. I don’t mind because, would you look at that volume knob! That, alone, is worth getting a desktop setup.

The knob also doubles as the power switch. An RGB light ring around the knob indicates the resolution of the audio file being played. The volume adjustment is partially digital, so you don’t have channel imbalance at a lower volume. However, there is a delay between the turning of the knob and the volume adjustment.

An interesting feature of the knob is that the volume increase is not linear. It ramps up slowly in the first half and then increases quickly in the second half. It means that even with very sensitive IEMs like Andromeda, I still have much room to adjust the volume. Meanwhile, many dongles tend to be super loud, even at 1/100.



Speaking of volume, K7 has two gain settings. I hear a slightly more dynamic sound with more depth from the high-gain,single-ended, with my U12T, using Hotel California as a test track. The difference is even more prominent with demanding IEMs like Final E5000.

Still, the difference between gain settings is not as severe as the Topping G5, so I don’t think you need to worry too much. I decided to keep the gain high since the volume adjustment range is still relatively large, even with the ultra-sensitive Andromeda 2020.



You can also use the DAC or the amplifier section of the K7 separately. For instance, you can feed analogue audio signals from a standalone DAC to K7 via the RCA line, then use the RCA output to pass the signal to the next device in your chain. For this use case, you need to switch the output of K7 to “PRE.”

You can also use the K7 as a standalone DAC by switching to the line-out (LO) output mode. The RCA output would carry the line output from the DAC section of K7.

I do not have a complicated hi-fi setup, so I use K7 as an all-in-one directly from my desktop. I use it for IEMs, headphones, and my active speakers.



K7 is surprisingly large if you are used to petite portable gears. Against desktop competitors, the size of the K7 is more reasonable. From memory, the total volume of K7 is roughly the same as the Schiit Magni Modi stack and slightly less than the iFi Zen stack. K7 is way smaller than the Schiit Modius Magnius stack.

I find K7’s build quality assuring. It has a metal chassis that is cold to the touch but does get warm after a song or two. All buttons and switches are firm without any play or rattle.

Sound Performance​

Gears for A/B tests:

• 64 Audio U12T (12.6ohm, 108dB/mW)
• Campfire Audio Andromeda 2020 (8.7ohm, 122.5dB/mW)
• Final Audio E5000 (14ohm, 93dB/mW)
• TGXear Serratus (300ohm)
• Apple USB-C to 3.5mm dongle (3/5 benchmark - Average)
• FiiO KA3 (4/5 benchmark - Good)
• Topping G5
• Shanling M6 Ultra

Playlist for A/B tests: IEGems Playlist

The overall tonality of the K7 strongly reminds me of the Apple dongle. K7 sounds natural with proper note weight. It does not emphasise the high frequencies and reduce the midbass like some ESS-based dongles or my Topping G5. The treble region is extended and detailed without edginess, “grit”, or “glare”. At the same time, K7 does not have the deliberate colouration that adds a warm hue to the sound like Shanling M6 Ultra.

As a desktop DAC/amp, K7 can provide most IEMs that “desktop effect,” making the soundstage larger and instruments more separated. The crispness and separation of music notes across the frequency response, especially in the bass and upper treble region, are noticeably better than an average dongle. However, the degree of improvement you can hear depends significantly on the specific IEM you use.

We discuss some archetypes of IEMs and how K7 handles them below.

Average IEM and earphones (5/5)​

I use the 64 Audio U12T to represent an average IEM. A unique feature of U12T is a proprietary circuit called LID which ensures that the IEM’s tonality remains the same across multiple sources, regardless of sources’ output impedance. This feature makes U12T a uniquely valuable instrument to pinpoint deviations or colouring deliberately introduced by a source.

For the first test, I compared K7 with the Apple dongle, using Hotel California as a test track. At a glance, both devices sound very close. The tonality is identical because of the LID circuit within the U12T and the similar tuning of the K7 and the Apple dongle. The differences between K7 and the Apple dongles lie in note definition, separation, and bass response. These differences became apparent only after multiple back-to-back A/B tests. After pinpointing the differences, I couldn’t stop hearing the issues; thus, the Apple dongle became less appealing.

The most significant differences between K7 and the Apple dongle are the texture and details in the bass response. With the K7, I can hear the texture in the decay end of the kicks and easily separate the bass guitar from the kick drum. With the Apple dongle, the textures of the kicks are less apparent, and the bass guitar is not as clearly separated from the kicks. The sense of layering of instruments from closer to further away is also more robust with K7. The Apple dongle tends to place instruments on a few planes that are closer together, so the 3D effect of the soundstage is reduced.

Detail-rich classical recordings, such as Flute Partita in A Minor, BWV 1013: IV. Bourrée anglaiseperformed by Emmanuel Pahud, highlight the performance gap between K7 and the Apple dongle more than rock or commercial music. With K7, flute notes are more crisp and well-defined, and treble air details are precise and highlighted. There is a sense of realness and 3D that U12T can bring out with the help of K7, but not with the Apple dongle.

The performance gap between K7 and KA3 is similar in type and magnitude to that between K7 and the Apple dongle. With the flute partita, I can hear more ambience and reverberation of the room with K7. The treble response of KA3 has some “grit” that prevents the treble air from being rendered as clearly and highlighted as the K7. The clarity of flute notes is also higher on K7, albeit not much. I also hear a gap in bass texture and separation between K7 and KA3. Still, it’s difficult to spot without careful A/B and critical listening.

Conclusion: 5/5 - Excellent. K7 out-resolves both an Apple dongle and a good dongle, such as KA3, across the frequency spectrum. K7 can add a bit of oomph to the soundstage presentation. However, the sound quality gap between K7 and a good dongle is very minute when driving an average IEM.

Low-impedance, high-Sensitivity IEM (4/5)​

Andromeda 2020 is a notoriously picky IEM. It easily reveals the hissing noises of an audio source. It is also sensitive to the impedance of the source and the cable itself. Connecting to a mismatched audio source can ruin the sound signature of these sensitive IEMs or at least prevent them from revealing their full potential.

What can a device like K7 offer the Andromeda that the Apple dongle cannot? Two things: bass and separation. In the iconic opening of the Hotel Califonia, I immediately noticed stronger and more physical kicks with K7. On the other hand, the kicks with the Apple dongle are barely recognisable. Guitars and vocals have more precise note attacks and extended decay with K7. The separation between foreground and background, such as between the band and the audience’s cheer at 3:00, is also more distinctive with K7. As a result of these differences, the Andromeda feels more lively and 3D with K7 compared to the Apple dongle.

The gap in resolution and separation between KA3 and K7 is slimmer. However, the KA3 still cannot power the bass kicks of Andromeda like K7. Due to the bass, I would say Andromeda sounds better on K7 compared to KA3.

Whilst the sound quality improvement is a welcome upgrade, the critical advantage of K7 is the volume control. With most dongles, I need to turn the volume to a very low level to avoid blowing my ears out with the Andromeda. There have been times when I don’t have a volume level left to reduce when a track is mastered with too high volume. With the dongles, I also lack the granular volume control offered by K7’s knob.

K7 is not perfect, though. When I turn the volume very low, even at low gain, I hear a slight hissing noise. At high gain, the hiss is more prominent. You are unlikely to notice the hiss when listening to loud and dense music, such as Hotel California unless you actively look for the hiss. However, the hiss on the high gain is very prominent with sparse recordings such as Flute Partita in A Minor, BWV 1013: IV. Bourrée anglaiseperformed by Emmanuel Pahud.

Conclusion: 4/5 - Good. The K7 does an excellent job of revealing the full potential of Andromeda. However, it is held back by the noise floor.

Low-impedance, low-sensitivity IEM (5/5)​

Despite the petite appearance, Final Audio E5000 is one hell of an IEM to drive. Low impedance, low sensitivity, and significantly bass-boosted make a nasty combination. You can get the midrange 1kHz region loud with even an Apple dongle. However, the bass would become muddy, making the E5000 blunted, fuzzy, and congested. That’s not how these IEMs should perform. When powered by the proper desktop amplifier, E5000 is a bass-head dream with an overwhelming amount of tight and deep bass. The clarity of the midrange and treble region is also more than adequate, and the soundstage is broad and deep.

K7 drives E5000 like a champ. In fact, the description above regarding how E5000 should sound is based on how K7 drives these stubborn IEMs.

The differences between K7 (high-gain) and Apple dongle are immediately noticeable when replaying Hotel California, centering around aspects. Firstly, the depth and layering of the soundstage. The Apple dongle does not convey any sense of depth and layering, pushing the primary vocal right up to my face. The K7 conveys a strong sense of depth, putting the main vocal in front of me as if I’m listening to a 2-channel system. K7 also renders a strong separation between the band in the foreground and the audience’s cheers in the background.

Secondly, the kick drums sound tighter and deeper on K7. The Apple dongle renders kicks and bass guitar as loud “thud thud” sounds with fuzzy attack and long decay. K7 tightens up and extends the bass deeper into the sub-bass, making you feel more bass whilst reducing the boominess.

Thirdly, K7 increases the clarity across the whole frequency range. Instruments and vocals become easier to track. More nuances are revealed.

The gap between KA3 and K7 is smaller and requires more careful A/B tests. Using Hotel California again as a test track, I found that K7 and KA3 place main vocals almost the same distance. However, K7 conveys a stronger sense of layering between the band and the audience. E5000 also sounds more detailed and vibrant on K7. Guitars have more brightness and bites. The cheer of the audience comes across more clearly and detailed.

High-impedance earbuds (5/5)​

Serratus is a pair of 300ohm flathead earbuds made by a fellow head-fi reviewer known as tgx78. These earbuds have achieved legendary status amongst enthusiasts due to their resolution and soundstage imaging. It’s also excellent for testing the ability of an amplifier to drive high-impedance devices.

Since the Apple dongle does not have 4.4mm termination, I will skip and focus on comparing K7 and KA3. With Hotel Califonia, I immediately hear a larger soundstage with K7. The band sits further from me, and all instruments are spread out, creating a nice 3D illusion. KA3 feels more congested in comparison. Vocals and guitars sound duller and less detailed with KA3, even though the KA3 sounds more “trebly” than K7.

Using Flute Partita in A Minor, BWV 1013: IV. Bourrée anglaise as another test track, I can confirm that K7 has more richness in the lower end and more details in the top end comparing to KA3. The concert flute has more warmth and body. The reverberation of the flute in the recording hall is also crisper and more detailed, adding a strong sense of ambience to the performance.

In conclusion, K7 drives 300 ohms loads to the next level compared to an average USB dongle. 5/5.

Valuation​

At the time of writing, K7 retails for less than any other entry-level desktop setup in Australia, such as the Schiit Magni Modi stack, iFi Zen stack, JDS Labs ATOM, and Topping D50+A50. As an IEM listener, I found that these desktop setups mostly perform at the same level with only slight differences. Because I am an IEM listener, I appreciate the 4.4mm output more than XLR or 6.35mm (only) output. Finally, suppose you go with a stack. In that case, you must account for the RCA interconnection cables and additional wiring for the power supply. Therefore, I consider K7 as the best value product within this category.

Conclusion​

Should you get a K7 if you only listen to IEMs? It depends on whether you have a desk setup at home or office. If you have a fixed spot where you sit down and work on your computer daily, a desktop DAC/amp like K7 is a good addition. The sound quality improvement, however slim, is there. The key benefits are quality-of-life improvements such as the volume knob, the wide adjustment range for sensitive IEMs, and flexibility. And the most important of all is the peace of mind, the freedom from the nagging thought, “am I bottlenecking my IEMs with these dingy dongles?” It’s hard to bottleneck your IEMs when you drive them with a beefy desktop device. Recommendation without reservation.

Pros:

• Volume knob!
• A lot of volume adjustment range for sensitive IEMs
• Extract the most sound quality out of your IEMs
• Versatility
• Assuring build quality
• Price

Cons:

• Hiss on high-gain with ultra-sensitive IEMs

Updated: March 25, 2023

The review sample was kindly provided free of charge in exchange for an honest review.
I didn't receive monetary or any other kind of compensation and I don't use affiliate links.
The price of the FiiO K7 is $199.99 and you can buy it from here.



FiiO K7

As always with FiiO we skip the lengthy introductions because they are so well known that they don't need one.

The FiiO K7 is the balanced version of the much acclaimed K5 PRO ESS which is one of the best selling FiiO desktop DAC/amps.
For the K7, FiiO have ditched the ESS chip for two pieces of the new AK4493SEQ DAC chip from AKM which is the newest version of the AK4493.
The FiiO K7 has a six-stage audio circuit with truly balanced analogue and digital sections.
Using two pieces of the same THX AAA 788+ amplifiers as the K9 Pro, the FiiO K7 is capable of outputting 560mW into a 300 Ohm load at 1% distortion and 2000mW into 32 Ohm load at 1% distortion from the balanced output.
The XMOS XUF208 input controller uses dual clock management to handle various audio formats.
The K7 can decode 32-bit 768kHz PCM and DSD512 but there is no MQA support.



The K7 features a power design consisting of multiple independent stages, with the voltage of each stage regulated by low-noise LDOs. Feeding this power design is an external 12V switching power supply. All in all, the K7’s power design supplies plentiful, clean power for an extraordinary listening experience.
Overheating, overload, and DC protection systems ensure that the K7 always operates at its best, so you can always enjoy a worry-free listening experience.
Thanks to its ADC curve reconstruction, the volume potentiometer features 112 smooth steps of adjustable volume free of channel imbalances and noise.



Appearance and build quality

The K7 is just slightly larger than the K5 and it features an all-aluminum alloy construction, carefully finished with CNC and other processes.
It has an excellent build quality and a smooth finish with an elegant black color that is perfectly complemented by the gold accents of the THX and Hi-Res Audio badges.
The circular RGB indicator light is capable of displaying single colors as well as mixed colors, with a unique light flow effect during power on/off or input switching.
Blue for ≤48kHz, yellow for >48kHz and green for DSD.
The K7 will not communicate with the FiiO control application so there is no way to disable or dim the RGB light.



User interface

This is a pretty simple to use DAC/amp with three digital inputs (USB, coaxial and optical), a line level input, a line level output and two headphone outputs.
Except for the volume control knob, that also acts as the on/off switch, there is a button for selecting between the various inputs and two toggle switches, one for setting the gain to high or low and another for selecting the desired output (headphone, line out or pre out).
At the right side of the front face there are located the two headphone outputs, one balanced 4.4mm and another single ended 6.35mm.



Accessories

The K7 comes bundled with an external power adapter, a USB cable and a 6.35mm to 3.5mm adapter.

Associated gear and power output

The K7 can do 1.2W/32Ω from its single ended output, exactly the same as the K5 PRO ESS, while the balanced output is almost doubling to a whole 2W/32Ω.
So it can run pretty much anything except for some exotic headphones and at the same time it is very silent with excellent channel balance.
I have used various earphones to test the performance, like the FiiO FD7, the Penon Vortex and the Meze ADVAR.
A mid gain setting would be nice to have for better headphone matching but I am really nitpicking here.
I did most of my listening tests with the Focal Clear Mg, the HiFiMan Ananda Stealth and the Meze 109 Pro, all of them with pure silver cables made by Lavricables.
As an example of the power output, with the Focal Clear Mg I never needed more than ¾ of the volume range at the low gain setting to get very loud and with excellent driver control while listening to classical music.



Listening impressions

FiiO has a great expertise with the AKM DAC chips and you don't have to listen a lot to the K7 to understand what is really happening.
A perfectly balanced and neutral tuning with a touch of warmness and a more natural timbre than the K5 PRO, make the K7 one of the most musical and engaging sounding FiiO products.
This is the old beloved FiiO house sound with the AKM flavor that I bet that many of you have been missing during the recent switch to the ESS chips.
A DAC that is perfectly capable of a clean and transparent sound with a mirror-like source fidelity but without sounding clinical, artificial or metallic.
The timbre is very natural and realistic, almost analogue-like and quite organic with plenty of harmonic variety and a colorful tonal palette.
The K7 is highly successful in connecting the listener to his favorite music while it offers very good technicalities for the category.



The bass is extended, fast, tight and controlled with excellent definition and clarity while it sounds quite full bodied and weighty, definitely more visceral than the K5 PRO ESS.
It is dynamic and impactful, certainly not that powerful and authoritative as some other DAC/amps with discrete output stages, like the Aune X1S GT or the Yulong Aurora but still very contrasted and definitely satisfying with bass intense music.
The mid-range is open sounding, lucid and sweet with a high quality texture and fine articulation.
The K7 offers plenty of resolution and refinement for the category with a high spirited and energetic treble which is kept smooth and controlled with a minimum digital glare and without harshness despite the excellent clarity and its luminous nature.
The K7 is very versatile and a great match with every headphone and all types of music, from modern electronic stuff to classical.
I have listened to dozens of recordings and I really remained impressed with the consistency of performance, from favorite rock tunes together with the Meze 109 PRO to the highly demanding Bruckner's symphony No.9 with the Focal Clear Mg.



The K7 is surprisingly open sounding with an expansive and quite grand presentation with excellent ambient information and a rather sharp imaging especially from the balanced output.

Single ended vs balanced

The single ended output is excellent sounding and very competitive, you shouldn't be worried at all if you plan to buy the K7 for single ended only use.
But you are still greatly encouraged to upgrade to the balanced, when possible, because it is technically superior, more expansive and articulate with an effortless power delivery that results in a more dynamic and controlled sound with extra headroom.

As a headphone amplifier

Using the line level input and taking the internal DAC out of the equation, the K7 is a very competitive analogue headphone amplifier and preamplifier with great transparency and a sound signature that shares a lot in common with all the characteristics as described above.
A nice option that allows the owner to use an external DAC or a vinyl set-up.

The icing on the cake

I know that spending another $150 to add an LPS to a $200 DAC/amp is a little hard to swallow but trust me that it is worthwhile.
The addition of the FiiO PL50 raises the performance even higher as it makes the most out of the K7 by adding a blacker background that offers deeper detail retrieval.
Additionally you will hear more impactful and contrasted dynamics, fuller and weightier sound with an even more realistic and natural timbre.
No, you don't need the PL50 to really enjoy your K7 but if you manage to get one at some point in the future then you are going to have a system with a performance level that is quite close to much more expensive products like the FiiO K9 PRO.



Compared to the K5 PRO ESS ($209)

The K7 is fuller sounding than the K5 PRO ESS, especially in the bass department but not exclusively so because the whole frequency range is conceived as more intense and weightier.
The timbre is also slightly more realistic in the K7, the sound is a touch more musical and less artificial, it is also more resolving and refined than the K5 PRO ESS with a larger and grander soundstage.
The differences are audible from the single ended output while the balanced raises the bar even higher.
The initial launch price of the K5 PRO ESS was $219 but after the release of the K7 the street price was lowered to $149.
So the K7 is about $50 more expensive but they are not that much when considering that they buy you a slightly better sounding and more versatile product.
In my opinion, the release of the K7 has made the K5 PRO ESS pretty redundant and obsolete, the only reason for buying it is if your budget is really strictly limited.



In the end

The release of the K7 marks the return of FiiO back to their roots where everything has started.
The AKM DAC chips, in my opinion, better suit the FiiO house sound and the K7 is the living proof of it.
A bullseye for the company, the K7 is one of the most competitively priced DAC/amps in the market right now and it combines a very musical sound signature with great technicalities, great versatility and excellent power delivery.
FiiO is also preparing a Bluetooth version with a minor price increase.
I am pretty sure that the K7 is going to surpass the K5 PRO in sales and become the most successful and best selling product of FiiO ever.
My only wish now, is that they are back to the drawing board already designing the successor to the K9 PRO with AKM DAC chips.

Test playlist

Copyright - Petros Laskis 2023.