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The K5 desktop amplifier made its debut in 2016. The "Pro" version, on the other hand, is an innovative product that incorporates Asahi Kasei branded driver circuits in the same chassis. The K5 Pro does not have a docking station allowing the K5 model to host a FiiO player that acts as a converter. The new model is a desktop-only unit, with 1.5W output power in the 32-ohm range, three levels of gain control, three digital inputs and outputs, analog inputs and outputs, and support for music up to 32-bit/768kHz.
The FiiO K5 Pro desktop amplifier certainly has many advantages. The visual design, ergonomics, powerful performance, three-level gain control, and various interfaces are impressive. As a result, this is a powerful amplifier that should be an excellent desktop amplifier. As good as it appears, this amp is not versatile enough to meet everyone’s needs and has a few drawbacks to consider that we’ll discuss in this FiiO K5 Pro review.
FiiO K5 Pro Affordable Desktop Amplifier Review
DAC: AK4493 | USB interface: XMOS XUF208 | AMP: OPA1642 + TPA6120 | Output power: 1.5W/32 Ohms | Recommended load impedance: 6 – 300 Ohms | Frequency range: 20Hz ~ 80kHz | Output impedance: ≤ 1.2 Ohms | THD + noise: ≤0.004 | Signal-to-noise ratio: ≤0.004 >115 dB | Channel separation: ≥75dB | Background noise <8µV | Maximum output voltage: 19.7Vp-p | Maximum output current: >500mA min | Input connectors: USB, S/PDIF, line | Output connectors: 6.3mm headphone output, 2 RCA lines | Max Resolution: PCM up to 768 kHz/32 bit, DSD up to DSD512 | Power supply: external power supply, 15V DC | Weight: 436g
The K5 Pro is a fairly budget device, so it comes in a simple cardboard box. However, the content of its package is spectacular, which is never a bad thing. Inside, of course, you will find the amplifier itself as well:
- External power supply
- Power cord with a country-appropriate plug
- Silicone pads
- USB cable
- A plug for the optical S/PDIF
- Adapter for 6.3 mm jack
In short, everything you need for everyday use is included.
The appearance of this device is very simple but not without charm. It is designed to be placed comfortably next to other audio devices or even a laptop. The case is made of dark gray aluminum and has a parallelogram shape with rounded corners. The build quality is good in the traditional sense. It doesn’t weigh much, but it adheres well to surfaces thanks to the padding on the bottom.
For operation, you have to install the driver from the manufacturer’s website, but it’s a seamless process that only takes a few minutes. All the controls are on both sides, as they should be. There are two switches on the front panel, the first to select the input and the second to change the gain (conveniently at 0dB, +6dB, and +10dB). There is also a volume control between the multicolor indicators.
The ring indicator around the wheel is moderately bright, and its color indicates the resolution of the signal reaching the input of the device. Three colors indicate the operation of the device and the quality of the track.
- Blue indicates sampling up to 48 kHz
- Yellow above 48 kHz
- Green corresponds to music in DSD format.
Unfortunately, the display can be annoying in the dark, and a small LED dot would be more convenient. The unit doesn’t come with remote control, so you have to set it up first, but for this price, it’s forgivable.
The button itself has a smooth stroke that allows you to select the appropriate volume easily. In the zero position, the knob turns the device off. The NJRC NJW1195 is a very low noise volume control chip with a noise floor of -118dB and adjusts the volume in increments of 0.5dB. Interestingly, the volume control implementation works in the analog domain of the digital circuit. This ensures excellent channel balance and the absence of distortion during adjustment.
On the front, there’s also the usual 6.3mm headphone output – FiiO decided not to make a balanced amplifier, probably because the K5 Pro already has plenty of power reserve.
On the back are power, USB, optical S/PDIF, and coaxial connectors, as well as a pair of RCA line inputs and outputs. With these RCA outputs, the FiiO K5Pro DAC headphone amplifier can also be used as a preamplifier. In this way, the K5 Pro can easily serve as both a DAC and an amplifier.
The device performs quite well in practice, but some features could have been implemented better. When you want to plug or unplug the K5 Pro desktop amp, it has to be held as it may move – the “rooted” feeling created by a high-end amplifier’s heavyweight is not here. Also, the LED ring is too bright, and the colors are vivid. The amplifier might be suitable for a gaming setup.
This unit is designed to be compatible with most headphones and is claimed to have increased output power. The newly developed XMOS XUF208 USB decoder has a new signal timing circuit, the NJRC NW1195A analog circuit with a level of 0.5 dB per step volume control, and the output noise of 118 dB is responsible for controlling the system volume.
An OPA1642 JFET op-amp is used to amplify the headphones, with additional voltage and current amplification provided by a TI TPA6120 op-amp to achieve a total output power of up to 1.5 watts into a 32Ω load. According to the manufacturer, the FiiO K5 Pro offers greater audio clarity and transparency with independent left and right audio channel processing and fully differentiated audio output.
By adding an external power supply of +/-15V and up to 1.6A, the K5 PRO can provide your headphones with power output. Even more appealing, FiiO introduces a 0dB gain (low gain setting), which should be useful for IEMs and highly sensitive headphones.
The presence of a powerful headphone amplifier suggests that the K5 PRO is primarily intended for use with headphones, but you can also connect speakers using an external amplifier.
The FiiO K5 PRO has a fairly linear monitor sound that reproduces the recorded audio flawlessly, which means it doesn’t add any embellishment or coloring to the sound. In addition to the very coherent and integrated presentation, other sonic features are also notable.
The bass range is well extended and manageable (1.5 watts is no walk in the park, though; it’s almost always present, sometimes even split into at least two parts). At the same time, there’s enough bass to have a good sense of density and weight without being too powerful. Instruments are nicely textured, and the soundstage isn’t too smooth or blurred.
The FiiO K5 Pro is fairly neutral, with a very clear midrange. The mid-range is as good as you’d expect. You can hear good detail in this frequency range, both in vocals and instruments. The frequencies in this range are not pushed back or hidden; they are presented neutrally, with equal priority given to the low and midrange frequencies. Modern manufacturers rarely mess up the midrange, and Fiio is no exception.
There’s also a good treble extension, which is detailed enough to convey the nuances of a recording. Instruments are nicely contoured, coming in and out and have a quick, precise attack. At the same time, there is no excessive harshness. The sound is very natural and organic.
The soundstage has medium depth and width. FiiO K5 Pro does not produce a broad soundstage or balanced sounds like the more expensive units: Marantz PM7000N, Burson Audio Conductor 3x, or Burson Playmate. The K5 Pro’s highs are sharper, less natural, and thinner than those units, but just as direct, fairly accurate, and resolved. The Playmate Everest, for example, is more spacious, with more pronounced bass and softer, natural highs that are not at all digital, whereas the K5 Pro is more artificial, harsh, and unbalanced. But given that Burson Playmate Everest costs almost twice as much, the K5 Pro is not dishonored.
There’s nothing wrong with the bass and midrange, but the treble has a very harsh digital sound character. Because of that, the sound tends to be cold, with the highs being more accentuated than the lows. As a result, the K5 Pro doesn’t work well with all headphones, and it’s easy to hear unnatural sounds on “harsh” or “airy” headphones. However, suppose you use the K5 Pro as a digital-to-analog converter for an external amplifier. In that case, you can expect a smoother, more linear sound without the harsh digital character in the highs.
The FiiO K5 Pro costs about $150. However, for its potential, the amplifier has great value. This should be a successful purchase if you like bright, clear sound or decent headphones with deep bass. Otherwise, the K5 Pro’s sound can be too bright, too harsh, and too artificial. The same goes for the entry-level model in the series, the K3; the latter also suffers from digitally harsh peaks. Perhaps a power supply change would improve the K5 Pro’s sound, but that would increase the cost; it’s already more cost-effective to opt for another desktop integrated amplifier, such as the Pioneer A-40AE.
The K5 Pro is better suited to warmer, darker headphones, with richer bass and less treble. You can also choose high-quality, well-balanced headphones, but the sound will become cooler with color-neutral headphones. Bright, neutral headphones should be avoided because they will most likely become too harsh and noisy.