FiiO K5 Pro ESS
FiiO K5 Pro ESS
FiiO K5 Pro ESS

FiiO K5 Pro ESS Review: Exceptional budget-friendly DAC

FiiO K5 Pro ESS

In this review, we’re diving into the latest offering from a Chinese audio powerhouse that has made a name for itself over its 17-year history. Known not just to audiophiles but also to a broader audience of music enthusiasts, this manufacturer boasts a vast array of audio products. Their lineup includes an impressive range of headphones, digital audio players, and digital-to-analog converters (DACs), available in both portable and stationary formats. They cater to a wide spectrum of price points, ensuring that regardless of budget, there’s likely a product that aligns with consumers’ financial and audio quality expectations.

This article was made in cooperation with Soundmag.

Unpacking and packaging

The box has a recognizable appearance, featuring a black hue enhanced by a holographic shimmer that displays a spectrum of rainbow colors, which is quite appealing. Traditionally, the device’s outline is neatly illustrated, with the brand’s logo prominently placed in the upper left corner, while the Hi-Res emblem is situated on the right side, and the model name is inscribed beneath. The compact size of the box corresponds with the small dimensions of the device it houses. Within, besides the device, there is a small box that contains accessories.

Delivery set:

  • the DAC itself and the  FiiO K5 Pro ESS amplifier
  • power cable with a European plug
  • external power supply unit 15 V = 1.5 A, 22.5 W
  • USB B – USB A cable (for connecting to a sound source)
  • adapter from 3.5 mm to 6.3 mm
  • 4 rubber feet
  • user manual

Design, interfaces and controls

The design of the device is as minimalist as possible, with small design accents, such as slightly recessed front and rear panels, and a bezel on the potentiometer. FiiO K5 Pro ESS itself  has a small rectangular shape with rounded edges, it will not take up much space on a table.

From left to right we have:

  • toggle switch for switching inputs (1-USB/2-LINE/3-COAX,OPT)
  • gain levels – 1(0 dB)/ 2 (+6 dB) / 3(+10 dB)
  • the potentiometer is combined with an on/off relay, with a smooth movement, there is an indicator light around it that indicates the quality of the audio reproduction: 44.1 or 48 kHz – blue color, above 48 kHz – yellow color, DSD – green color. If the USB is not connected, the indicator lights up red
  • 6.3 mm output for headphones with an output power of 1.5 w into 32 ohms

On the back panel:

  • coaxial input
  • input optical(OPTICAL)
  • RCA line input for connection to type sources (CD/cassette players, etc.)
  • linear RCA output for active speakers, or passive through an amplifier
  • USB – B input for connecting to (phone, computer, laptop, tablet, etc.) But to connect to portable sources that do not have a USB A connector, you need an OTG – USB type C or OTG – Lightning adapter
  • input for power, through the complete 15 V external power supply unit



The K5 Pro ESS is equipped with the top-tier ESS ES9038Q2M portable DAC, boasting exceptional performance and a richer sound profile than its predecessors. It achieves a 50% reduction in distortion and a 3 dB enhancement in dynamic range.

Featuring the advanced XMOS XUF208 USB decoding chip, this device is capable of processing high-resolution audio up to 768 kHz and DSD512, along with offering both coaxial and digital inputs. This ensures that regardless of the audio equipment being used, users can experience the full advantages of digital signal integrity and fidelity. Notably, the K5 Pro ESS supports up to 96 kHz output on these inputs, accommodating a wide array of music players.

The device’s meticulously engineered audio architecture ensures superior amplification. It houses a spacious interior for its high-quality analog amplification components, including a four-stage audio circuit (second-order LPF, analog volume control, voltage boost, and current feed) for unmatched fidelity in its class.

For power, the K5 Pro ESS utilizes a 15V external power supply, specifically designed to minimize noise. The power input undergoes secondary filtering before independently powering the audio amplification and other circuits, effectively eliminating power supply ripple and reducing crosstalk. This design ensures stable, low-noise power essential for superior sound quality.

Volume adjustment on the K5 Pro ESS is finely tuned thanks to the reconstruction of the ADC curve, enabling smooth, precise control over volume levels without introducing noise or channel imbalance. This feature is particularly beneficial for headphones of varying sensitivities and impedances.

The device also offers three levels of amplification, adjustable via tactile switches (tumblers) marked for easy identification of the optimal setting for any headphones.

In terms of power amplification, the K5 Pro ESS stands out with its direct amplifier circuit, significantly boosting the output power of the TPA6120 op amp by over 60%. This results in a total output power of 1.5 W into a 32 ohm load and up to 20 V into a 300 ohm load, ensuring compatibility with both low-impedance in-ear monitors and high-impedance full-size headphones without compromise.


The FiiO K5 Pro ESS delivers a sound quality that pleasantly surpasses expectations, especially when considering its price point. This comes as a surprise, particularly when recalling my previous experience with the FiiO K9 ESS, which, although predictably excellent given its cost, only provided pleasant emotions without truly impressing. Turning our focus back to the subject of this review, the K5 Pro ESS, I’ll forego the traditional pairing specifics with headphones to highlight the DAC’s sound characteristics.

The DAC presents a vibrant sound profile, accentuating micro-contrasts to capture the minutest details in music, making it exceptionally suitable for tracks where such intricacies are appreciated. This suggests that pairing with moderately bright headphones could enhance the listening experience by bringing out every nuance.

However, this characteristic leans towards a non-universal sound signature, potentially limiting its versatility across different music genres. For a more balanced auditory experience, headphones with a subdued sound signature are recommended. Ideally, these headphones should de-emphasize the high frequencies, or avoid them entirely, while accentuating the lower frequencies. This is because the DAC itself doesn’t boost bass but focuses on the quality, speed, and technicality of bass reproduction.

In summary, pairing the K5 Pro ESS with bright headphones might compromise its multi-genre capability, leading to a sound that can be perceived as overly sharp and potentially fatiguing over time. Conversely, using headphones with a darker sound signature can smooth out the audio, enriching it with vibrant and pronounced accents in the bass and mid-ranges. This adjustment enhances the clarity and legibility of the music, creating a more enjoyable listening experience.


The FiiO K5 Pro ESS delivers an audio performance that is meticulously detailed across the frequency spectrum, making it a standout choice for audiophiles seeking precision and clarity in their listening experience.

– **Low Frequencies:** The bass is technical and unexaggerated, showcasing an impressive speed and quality in its rendering. This approach ensures bass lines are clean and defined, without overshadowing other elements of the music.

– **Mid Frequencies:** Midrange frequencies are presented naturally and transparently, offering a purity in vocal reproduction without any timbral distortions. Voices come through as slightly more immediate and brighter than in the original recordings, giving the impression that the artist has taken a step closer to the listener. This effect, along with a spacious soundstage and accurate instrumental positioning, enhances the overall listening experience.

– **High Frequencies:** The treble region adds dimension and microcontrast, contributing to a sense of airiness and realism in the music. However, as previously noted, it’s advisable to pair the DAC with headphones that aren’t overly bright to avoid any harshness or “sibilance” effects.

The K5 Pro ESS proves to be versatile with various audio qualities, performing admirably even with standard PCM 44.1 kHz tracks, ensuring no discernible loss in audio fidelity.

My personal use involved primarily connecting it to a computer, as well as to an Edifier R2000DB active speaker system for a broader listening setup. Employing slight equalization adjustments to the low and high frequencies further refined the sound, enhancing the soundstage, detail, and eliminating any minor distortions in the bass. The result was an exceptionally balanced and enjoyable sound profile. It’s worth noting that for those switching to speaker listening, removing headphones is all that’s needed without any need for additional adjustments, underscoring the DAC’s user-friendly design.

In essence, while the K5 Pro ESS requires a bit of fine-tuning (such as equalization for optimal speaker performance), the quality of sound it delivers, from its articulate bass to its pristine mids and detailed highs, establishes it as a compelling choice for those seeking a rich and immersive audio experience.


The FiiO K5 Pro ESS emerges as an exceptional budget-friendly DAC, offering a sound profile that is both bright and technically proficient. It excels in delivering a fast, clean, and undistorted auditory experience. Rather than focusing on punchy, overwhelming bass, it opts for a precise and speedy bass presentation, striking the right balance without sacrificing depth or detail. The midrange is tailored to perfection for those who prefer a straightforward, unembellished sound, avoiding unnecessary emphasis on any particular aspect. High frequencies are rendered with a lively brightness, injecting an alluring charm into each listening session that enhances the overall engagement with the music.

Moreover, this DAC stands out for its support of high-resolution formats, capable of adeptly decoding a wide array of audio files to meet the demands of audiophiles seeking superior sound quality. It boasts a comprehensive set of features, including multiple connection interfaces, catering to a variety of audio setups and preferences.

Packaged within a compact frame, the K5 Pro ESS’s offering at a $250 price point is indeed impressive. For audiophiles or music enthusiasts looking for a high-quality DAC without breaking the bank, it’s hard to envision what more one could desire. This device successfully bridges the gap between affordability and high performance, making it a highly recommendable option for those in pursuit of pristine audio reproduction.


Weight and size:

  • dimensions 120×146.5×55 mm
  • weight 480 grams


  • chip: ES9038Q2M
  • USB decoding chip: XMOS XUF208
  • output power: ≥ 1.5 W (32 Ohm)
  • output resistance: 1.2 ohms
  • coefficient of nonlinear distortion: < 0.0009% (UAC IN/SPDIF IN)
  • noise level: < 8 µV
  • signal/noise ratio: ≥ 118 dB
  • channel separation: > 80 dB (USB DAC/OPT/COAX)


  • RCA/6.3 mm




  • PCM from 44.1 to 768 kHz, DSD 64/128/256/512, DSD decoding
This article was made in cooperation with Soundmag.
FiiO K5 Pro ESS
FiiO K5 Pro ESS