Fosi K5 PRO Mini Review Stereo Gaming DAC

Friday, October 28, 2022

Give your headphones a new lease of life with a DAC amplifier - a neat way to boost fidelity and audio quality at the same time! The DAC amp seen pictured is the Fosi K5 PRO Mini - a self contained desktop DAC and amplifier combo, on budget and with useful features such as microphone support.

The Fosi K5 PRO Mini enclosure is entirely made of metal with a rear facing face plate and a front facing faceplate, which integrates three knobs, a microphone port, a 3.5mm headphone port and 3 status leds to indicate connection mode (USB, optical or coaxial). When connected to a PC, the mic and headphone inputs double as mic/audio passthrough ports. You can use them individually or as a combo with a PC splitter cable (included).  
Not all DAC amps come with microphone input, making the Fosi K5 PRO Mini an appealing proposition, specially for online gaming. The knobs are made of textured aluminum with a similar abrasive finish as a metal nail filer, making the the knobs grippy to hold with the fingers. The knobs sit on top of standard potentiometers with stops and tight turn shafts, which provide superb gradual adjustment. On the bottom of the Fosi K5 PRO Mini, there are four thick rubber feet to dampen vibrations. On the rear facing plate, you find a dual purpose USB-C port (for power and USB input), as well as an optical port, a yellow coaxial input and two RCA (red/white) audio outputs for speakers. 

The bass knob and treble knob integrate a tactile notch at the half way turn mark to indicate 50% setting. The volume/mode knob does not have a tactile notch but has an etched marking on the front of the knob to help identify the position of the knob at different levels. The bass and treble knobs also have an etched marking. When connected to a Windows PC, the volume on Windows does not sync with the volume knob. The volume/mode knob has centre button functionality for toggling between USB, optical and coaxial modes. The power output of the headphone jack is as follows:1000mw@16Ω, 500mw@32Ω, 300mw@64Ω, 150mw@128Ω, 80mw@300Ω.

The Fosi K5 PRO Mini can be powered via an AC wall adapter but, it is a bus powered device, meaning it runs using power from the connected device (e.g. PC, console, etc). The Fosi K5 PRO Mini dac amp emclosure measures 10cm deep x 8.5cm wide x 2.7cm high. The overall dimensions of Fosi K5 PRO Mini (including the knobs and ports) are 13cm deep x 8.5cm wide x 3.5cm high. The knobs stick out 1.2cm out and have a 1.2cm diameter.The weight of the Fosi K5 PRO Mini is 257 grams - similar to the Fosi Audio BT20A 2-channel integrated amp
As far as performance, the Fosi K5 PRO Mini dac amp supports most smart devices including consoles such as Playstation and Xbox One and Xbox One X/S. It does not work though, with the Xbox Series X/S because these consoles do not support Microsoft's User Account Control (UAC) feature. The K5 PRO Mini delivers clean sound with wide soundstage and separation, making it very easy to identify the bass, drums and voices in a music track. 

While the Fosi K5 PRO Mini DAC amp can handle low and high impedance headphones up to 300 ohms, there is a power output limitation at higher ohms. The Fosi K5 PRO Mini dac amp can only put out 80mW of power into a 300 ohm headphone. If you were to plug in, say, the Sennheiser HD800S headphones (rated at 300 ohms/ 102dB) into the Fosi K5 PRO Mini DAC amp, it will only be able to drive the HD800S headphones to 70dB, which is less than the 102dB the HD800S headphones are capable of.

 Potential deal breakers
  • Can only drive 300 ohms headphones to full power as long as the sensitivity is less than 80dB.
  • No gain switch
  • Only supports variable line out, which means you cannot use the Fosi K5 PRO Mini as a standalone DAC to feed a different amp
  • No status led light to indicate the quality of the audio being played.
  • Not enough to power the likes of 6XX and Sundara planars
  • No switch to change between outputs - line output and headphone ouput both play at the same time 
  • The 3.5mm headphone jack has low output power for high impedance headphones - it can only push out 38mw into 300 ohms. Plugging in a pair of headphones such as the Sennheiser HD800S headphones rated at 300 ohms/ 102dB means the headphone jack can only drive them to about 40dB, which is very low volume.

Selling points
  • Bus powered
  • Microphone input for online gaming
  • Headphone input
  • Audio/mic ports reinforced gold plated metal rings
  • Knurled metal knobs
  • Supports optical out and RCA out - perfect for running optical out from a TV and RCA to 3.5 adapter a set of speakers
  • Metal enclosure
  • Removable rear faceplate by undoing two hex screws
  • Bass and treble tone controls
  • Supports low and high impedance headphones (16 ohms and 300 ohms)
  • Up to 24 bit/ 96 kHz sample rate (via USB)
  • Up to 24 bit/192 kHx sample rate via optical/coaxial
  • Compatible with Windows computers, Mac computers, Nintendo Switch, PS5, PS4 and PS4 Pro
  • The line outputs and headphone output are both active at the same time. This can be a deal breaker but also a selling point if you run Windows 7 and like playing your computer sound through speakers and media player sounds through the headphone jack.
 The included cables are non-branded but have a premium feel. They include a 15cm PC splitter cable made with hard plastic plugs, rubber strain reliefs and rubber y splitter. The optical cable measures 1.5 meters. The 1.2 meter USB-C cable features a 2-in-1 plug to convert between USB-A and USB-C. You can buy the Fosi K5 PRO Mini from Fosi Audio and amazon.There is also a K5 Mini version, which has similar construction and hardware to the K5 PRO Mini but slightly cheaper. 

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