FiiO K5 Pro ESS Review

FiiO K5 Pro ESS Review

28 April 2022 0 By Petros Laskis

FiiO K5 Pro ESS Review

New chip – better sound.

Pros: + Excellent performing all-in-one device
+ Balanced and musical sounding
+ Power headphone amplifier
+ Great value for money
+ Can be used as a line level headphone amplifier
+ Three gain settings and excellent channel tracking
+ Silent background, suitable for IEM use
+ Better than its predecessor
+ Compact sized

Cons: – Not the most resolving
– Headphone amplifier could be more dynamic
– No MQA decoding (if you care)
– Internal low pass filters not accessible by the user
– No Bluetooth connection
– Not compatible with the FiiO control application
– The pre out is active together with the headphone output
– A better quality power adapter should be welcomed

The review sample was kindly provided free of charge in exchange for my honest and subjective evaluation.
I only covered import fees and tax.
The K5 Pro ESS price is $199 (€199) and you can buy it from


FiiO K5 Pro ESS

The FiiO K5 Pro ESS is a compact sized, high performance desktop DAC and preamplifier with a headphone amplifier.
This is not a new product, the original K5 Pro was launched back in 2019 and since then has been one of the best selling products of FiiO.
The original K5 Pro featured the AK4493 DAC chip but the AKM factory fire forced FiiO to exchange it for the ES9038Q2M from ESS, which is a chip with better technical specifications.


Technical highlights

The FiiO K5 Pro ESS features an XMOS XUF208 USB receiver which supports up to 768K/32Bit PCM and Native DSD512.
The unit also includes coaxial and optical digital inputs which support up to 192kHz.
The USB input supports OTG connection so you can use your phone or tablet as a source.

The internal circuit is carefully designed and optimized for the best possible sound quality.
It is a four level audio circuit which includes a second order low pass filter, analogue volume adjustment and ADC curve reconstruction with the NJW1195 , voltage amplification by the means of two OPA1642 OP-AMPS and headphone current drive with the known TPA6120 from Texas Instruments.

K5 Pro ESS uses a 15VDC external power adapter with the incoming DC power being filtered by a secondary power supply which then independently provides power to the amplifier stage and the rest of the circuit.

The large operating voltage, together with the feedforward amplifier circuit design, increases the power output of the TPA6120 by more than 60%, for a total power output of up to 1.5W/32Ω and a large voltage swing of 20Vpp at 300Ω.


I/O and user interface

The K5 Pro ESS is an all-in-one device that can be used as a DAC/Headphone amplifier, as a DAC/Preamplifier and as a standalone headphone amplifier through the line level input where you can connect an external source as a phono preamp.
You don’t get Bluetooth wireless connection and you can’t change the default low pass filter.


At the left side of the front face there are located two switches, one for gain selection between L/M/H and the other one for input selection between USB, coaxial/optical and the line input.
A one-piece all-metal oversized volume knob is positioned at the center of the front panel and is surrounded by a circular RGB light indicator which changes colors according to the input bit rate.
48kHz and below is blue, 48kHz and above is yellow and DSD is green.
At the right side there is the 6.35mm headphone output.
At the back of the unit you can see the RCA analogue output and the various inputs.(USB, coaxial, optical, RCA line IN and DC power)


Design, build quality and accessories

The K5 Pro ESS is a compact device measuring 120x130x55mm and made from solid CNC aluminium with a sandblasted black finish.
Build quality and finish are excellent while the volume knob, all interconnects and switches are of the highest quality and feel durable.
Inside the box you are going to find the power adapter, a USB cable, a 6.35mm to 3.5mm adapter and four adhesive rubber feet.
An RCA interconnect is not included.

Associated gear

As per usual practice the unit was left playing music for about 150 hours.
I have tested the K5 Pro ESS as a DAC/Amp and headphone amplifier through the analogue input.
ATM, I don’t have any active monitors or a power amplifier for testing the preamplifier function.
Various headphones and IEMs were used, including the HiFiMan Sundara, Sennheiser HD660s, Focal Clear Mg and FiiO FD7.
Steaming duties were handled by Silent Angel Munich M1T and Bremen B1.

FiiO K5 Pro ESS

Power output

The headphone amplifier is powerful and can easily drive most of the headphones except for some very inefficient models.
The gain switch offers three positions, the first one is 0dB and suitable for sensitive earphones, the second one is +12dB and the third is +16dB.
At the lowest setting, the amplifier is dead silent without hiss while the channel balance is excellent, so K5 Pro ESS is excellent for sensitive earphones.

Listening impressions

The ES9038Q2M DAC chip might be overshadowed by the much more technical and expensive ES9038PRO but I must admit that most of the times that I have encountered it, it sounded pretty special.
There is no coincidence that some of the best audio manufacturers, like Arcam or Musical Fidelity in the brand new M6x DAC, are using it in gear that costs more than $1K.
When properly implemented it can be technically accomplished and very musical sounding at the same time.

And this is what happens with the K5 Pro ESS which has a neutral and linear sound signature, with great technicalities for the category while it sounds musical and engaging.
The timbre is on the natural side and consistent throughout the whole audio band with a minor exception of some upper-mid/treble digital glare that doesn’t get too prominent.
The pitch is mostly accurate and acoustic instruments sound quite close to their real counterparts.

There is a hint of warmness and smoothness to the sound, with a non aggressive, easy going treble which nonetheless is definitely extended and not muted at all.
There is plenty of clarity and air between the notes, detail retrieval is certainly above the expectations while there is a good amount of intensity and natural decay.
The excellent clarity is persistent and equally present from the mids down to the lower end and music sounds well defined.
All parts of the frequency range are individually present without cross-layering that could result in masking but at the same time there is a great sense of cohesiveness and nothing sounds detached.
Instruments and voices – especially in the mid range – are heard emotionally deep and expressive with plenty of harmonic saturation and quite fine articulation.


The sound is full, almost visceral, not dry or lean with deeply extended bass which stays well controlled, tight and multi-layered.
Dynamics are sufficiently good but not the best, the overall impact is on the softer side and great bass drums or intense electronic beats don’t sound as physically imposing as it would be ideal but in the end you are not going to find yourself missing that lot.

Both the DAC and the headphone amplifier are fairly transparent, revealing and quite exposing but they don’t go as far as to become punishing.
Raw material quality is for sure very important if you want to maximize your experience but at the same time some poorly recorded songs will not give you a headache.

Soundstage is very good but not spectacular, the K5 Pro ESS will not bottleneck your particular headphone sound-staging abilities but it will not make it shine either.
The presentation is wide and spacious with accurate imaging and plenty of air around the performers so as not to sound congested but you will find it lacking in end game layering, scale and holography.
It must be said that the K5 Pro ESS performed equally well with all kinds of music and I remained very satisfied listening to classical music like this new recording of Ravel’s orchestral music.


Brief comparisons

K5 Pro AKM

Differences are not that pronounced but the new ESS version is more technically capable.
The sound is clearer, more tight, better controlled, there is some extra definition and it doesn’t sound as hazy and soft as its predecessor.
Dynamics are better and both ends sound more extended while the overall presentation is more realistic and impressive.
Now, I wouldn’t dare to go as far as to suggest that you should upgrade to the ESS model but newcomers rest assured that you are buying a slightly better version and this is definitely good.

TOPPING EX5 ($359)

You have to spend $150 more for the EX5 in order to get dual ES9038Q2M configuration with MQA decoding, LDAC Bluetooth connectivity and a remote control.
You also get really balanced XLR line output but you lose the line level input while the headphone amplifier power output is the same as with the K5 Pro ESS.
The XLR headphone socket is just for convenience and the headphone amplifier is not really balanced.
Sound quality is more or less on the same level but the EX5 has a slight edge when it comes to extra clarity, better definition and a touch more expanded and holographic soundstage.
Both units are worth the price of admission and you should dish the extra cash for the EX5 only if you need the extra features.


LOXJIE D30 ($260)

With the Loxjie D30 you are paying $60 extra in order to get a better specked DAC chip (ES9068AS) and MQA support.
The D30 is primarily a DAC/pre as the headphone amplifier is underpowered and rather mediocre compared to the K5 Pro ESS.
You also lose the line input and in exchange you get Bluetooth with aptX HD and a remote control while the D30 is the only one between the three which can have a fixed level line output and can be used as a standalone DAC.
Sound quality is more or less the same, maybe a touch more refined and technical with some enhanced clarity and definition between the lines.
Again you should carefully consider your needs in order to decide.

FiiO K5 Pro ESS

In the end

Nothing much left to add here, the K5 Pro ESS is a slightly enhanced version of a classic FiiO hit, worthy every last penny of the asking price.
With top notch sound performance and equally good build quality it is one of the best entry level “all-in-one” DAC/amps you money can buy, as long as you don’t care about MQA and wireless connectivity.

Test playlist

Copyright – Petros Laskis 2022.