FiiO K3 Review – Stationary Budget Desktop Amplifier

Written By Soundsight

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The FiiO K3 (formerly known as the E30) is the successor to the Olympus 2 E10k, is probably the best-known product from the Asian brand. The new DAC with amplifier is based on the Q1 Mark II model but is intended for desktop use. The new, smaller DAC/AMP is powered by USB Type-C, can play DSD files, operates in two USB modes, powers balanced headphones, and can act as a digital or analog converter.

The company seldom releases such products, usually favoring DACs and portable players. However, they have always had a line of small desktop units: the K3, E10, and E10K. The new model combines a traditionally compact size with a range of inputs and outputs (including 2.5 balanced audio). Things look good so far, but will this affordable USB Type-C desktop amplifier deliver on its promise?

FiiO K3 Type-C Compact Desktop Amplifier and DAC Review

FiiO K3 Specifications

DAC: AKM AK4452 | AMP: OPA1612 + 2 x OPA926 | USB chip: XMOS XUF208 | Frequency range: 20 Hz – 80 kHz | Output power: 120 mW/32 Ohms in standard output, 200 mW/32 Ohms in balanced output | THD + noise: ≤ 0.004% | Output impedance: <1.04 Ohms | Signal-to-noise ratio: ≥ 113 dB | Channel separation: ≥ 70 dB | Maximum output voltage: 7.39 Vp-p | Maximum output current: 81.6 mA | Recommended load impedance: 16 – 150 Ohms | Maximum resolution: up to 384 kHz/32-bit, DSD256 | Inputs: USB-C | Outputs: Coaxial, optical, 3.5mm headphones, 2.5mm balanced | Weight: 82g


The K3 comes in a simple white cardboard box with a lid and a picture of the DAC on top. All other non-essentials: the company logo and high-resolution audio icon are displayed at the top, while certification information and the minimum current input are displayed at the bottom.

Apart from the DAC itself, the company tried to keep the packaging as simple as possible

  • Two pairs of adhesive pads
  • USB Type-C cable

The USB cable has a matte coating and a narrow connector. The sticky pads are made of dense foam and covered with a thin layer of rubber. There are 4 pads (2 pads per set) attached to the bottom of the case.

Of course, we can draw attention to the absence of carrying pouch and elastic fasteners, but these things are rarely necessary for stationary Desktop amplifiers.

Design & Ergonomy

The first thing you will pay attention to is the device’s size. It does not look small in photos, but it is two to three times smaller than a regular PC mouse in reality.

The compact enclosure is traditionally made of black aluminum, and, as usual, all controls are located on the front and back. Build quality is not an issue.

Everything is well put together, and there is no vibration or wobble. The only real drawback is the lightweight – heavy cables can cause the K3 to spontaneously wobble on the table, but the rubber feet prevent that too much.

The K3 measures 7cm x 5.8cm x 2.2cm, which is quite small for a desktop amplifier. The whole device is very light (only 89 g), and the pads from the kit are quite slippery, enabling the K3 to slide easily across your desk.

The device could have used a little more weight and silicone pads instead of foam ones, making the amp more stable on smooth furniture.

On the front, there is an on/off switch, an LED button, two sliders (for boost and bass adjustment), and two outputs (3.5mm and 2.5mm). All elements are presented in a readable gray font that is unobtrusive to the eye.

On the back of the gadget is everything else (all elements are shown in a readable gray font).

  • 3.5 mm Line output
  • USB input (this time USB Type C)
  • Coaxial and Toslink optical outputs
  • The switch of USB Audio standard between the first and second versions

The FiiO K3 operates in two USB audio modes, selected via a switch on the rear panel.

  • Version 1.0 requires no drivers and supports files up to 24bit/96kHz. This mode is available for older devices and hardware that do not support USB 2.0 audio.
  • Version 2.0 already requires a light software download from the manufacturer’s website and supports 32bit/384kHz and DSD files (up to DSD256).

If you need higher resolution and DSD, you can enable UAC2 mode, but in this case, Windows users will need some drivers. As you can see from the outputs, the K3 can also be used as a USB converter for older DACs that do not have this input.

Overall, I’m satisfied with the features of the FiiO K3. There is no lack of balanced output, which is an important factor for a desktop amplifier. Also, the manufacturer offers 2.5mm cables in most of its headphones. There’s no shortage of line and digital outputs either.

5. Technology

The AKM AKM4452 digital-to-analog converter and XMOS XUF208 USB microcontroller are integrated into the device. Combined with a Texas Instruments OPA926 operational amplifier, the “coefficient of nonlinear distortion + noise” is 0.004%. The headphone impedance is 32 ohms, and it is possible to generate up to 120mW of power for the headphones.

The FiiO K3 is powered by a USB Type-C connector and a USB Audio 2.0 to USB Audio 1.0 mode switch. Headphones can be connected to the FiiO K3 via a 2.5mm balanced jack or a 3.5mm stereo jack.

I had no problems with the connection, but the FiiO K3’s specifications are very selective and require a synergy that most headphones don’t match.

The K3s will work best with warmer, darker, or bass-oriented headphones, though there are exceptions.

While there are exceptions, I recommend avoiding bright, airy, or harsh headphones, as they can sound dry and uncomfortable when paired with the FiiO K3 amplifier.

I wasn’t thrilled by the signal clarity. In this instance, I don’t recommend using headphones with high-impedance or balanced armature headphones.

The little FiiO desktop amplifier won’t power serious, demanding headphones, so the K3 will work with most in-ear or entry-level headphones.

Other weak points of the device are its dynamics and power. According to the manufacturer, the FiiO K3 can handle headphones with impedances up to 150 ohms.

I had no problem, as the FiiO K3 was able to handle the 250-ohm version of the Beyerdynamic DT990.

However, it should be noted that the dynamic range of medium and high impedance models is average, while more refined models can become dull when they lack power. This is an almost impossible problem to solve because of the USB power supply and its limitations.

The engineers at FiiO still did a great job because, overall, it’s hard to point significant weaknesses. The FiiO K3 amplifier is simply an excellent device.

Sound Quality

Compared to its predecessor, the FiiO K3 greatly improves sound quality, but its features have also changed. It’s a less musical, more analytical device that exposes the weaknesses and strengths of the records it plays.

The biggest change from its predecessor is in the bass, which has become a bit thinner, more compact, and more technical.

The trebles and mids have been lowered and reduced to the background, but the sub-bass has been raised a bit for a more detailed and textured sound.

These changes take a lot of energy out of the bass. The sound is now cooler and less musical, and depending on your repertoire and personal taste, this change can be considered positive or negative.

The sound is soft and intimate, with a small soundstage, next to which we are positioned very close. This is not a problem, as the sound is clean and coherent and does not lack air even with dark, closed-back headphones.

With the FiiO E10K, there are noticeable gaps between the channels that can interfere with the stereo experience, but that is not the case here.

Similarly, with the E10K, there is a noticeable gap between channels that spoils the stereo experience.

But with FiiO K3, the acoustic separation is excellent. Each instrument was easily identifiable, although the boundaries between them were not very clear.

In the end, the sound is not as impressive as I expected. Everything is spoiled by the treble response, which is poorly controlled, humming, and too sharp – few headphones can fit perfectly with FiiO K3s, and even when the treble is smooth, one can still pick up on the lack of control of the sound.


The FiiO K3s is an excellent offering and a great evolution from its predecessors in terms of features and sound quality. Unfortunately, despite the device’s large number of ports, the higher price and more analytical nature may make it difficult for the device to achieve the success of its predecessor.

If you want to use a DAC/amplifier with full-size headphones, FiiO K3 is not the most competitive amplifier and certainly not the best for your needs. The sound of this DAC is also not as colorful as the cheap devices, but that makes it a good choice for those looking for a neutral amplifier.