Fosi Audio K5 pro mini gaming DAC/ Amp

Disclaimers

This is a loan unit. I don’t own this Amplifier. This review is completely subjective.

Build

Fosi k5 pro is fully made out of metal. Really good build quality.



Equipments used for this review

Fosi K5 Pro, Hiby x F.audio Ace, Simgot ew200, Simgot ea500, Hifiman He400se, Creative Aurvana Live SE


Sound-Tonality and Technicalities

Yeah, umm… K5 pro is a big NO for me. Because I can't find a great thing about this amplifier. It sounds bad, resolution is below average, bass and treble extension knobs are useless for me because when you use those things, it will sound worse. Nothing to talk about, because k5 pro just sounds really bad. Only good thing is the amplification but it can’t even drive a planar headphone at high volumes…. It just starts clipping.


Conclusion

Not much to talk about. Just another bad headphone amp. Bad job Fosi.

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Video Version of this review if you don't like reading:

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Disclaimer
This unit has been provided free of charge by Fosi Audio in exchange for my opinion.
The following is an account of my own personal experience with the product.

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Intro
The ‘K5 Pro Mini Stereo Gaming DAC’ is directly aimed at the entry level gamer-focused audiophile.
What makes it stand out from the crowd, especially at this price point is a range of audio inputs, including a 3.5mm front-microphone port for headsets.
However, what truly stands out for me in a product at this price point is the inclusion of bass and treble tone controls; more on those later.

Specifications for the K5 Pro can be found on their website:
https://fosiaudioshop.com/products/...aming-dac-hifi-headphone-amplifier-microphone

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Build, Design & Ergonomics
I get the impression that most of the cost went under-the-hood of this product.
It comes with a pretty standard aluminium shell, however it is tastefully finished with the front facade perfectly matching the body and the text is fairly well subdued on a grey/silver version.

The control knobs however do feel a tiny bit loose, so it feels something like a little mechanical backlash before the turning actually takes control of the sound – in practice you’re not going to really focus on this at all if you’re just making quick adjustments on-the-fly.




Inputs
On the rear of the unit, the cinch output sockets and coaxial input sockets are notably fine. They do not have obnoxiously strong hold over plugs like some other RCA sockets.

The USB-C port is OK; the cable isn’t seated perfectly snugly, but this is a common theme even on mobile phones that cost over 1000 euros, so for a stationary desktop unit, this is more than acceptable.

Since I was using the K5 Pro at my PC, this review will be based around it’s USB functionality.
I do not own any products with optical or coaxial output, so that part will not be part of this review.


Other
The rubber feet are a nice addition that I wasn’t expecting on a product at this price point, however they didn’t prevent the unit from sliding around on my glass monitor stand base, but I still greatly appreciate the scratch protection.

The blue LED is quite bright compared to other products I own, and might be distracting for some people if placed close by or directly in front of you. I found it to be a bit distracting late at night.



And finally, due to the small size of the unit, some might find that it is impossible to turn the control knobs without raising the unit off it’s resting surface.
Mine was perched a little higher off my desk on the edge of my monitor stand base, so that was a non issue for me.

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Functionality
Installing the DAC was as simple as plug and play, however it will need a dedicated USB port for power. It will not turn on if it has to compete for power through a passive USB hub.

After installing, it does not behave differently to other DACs I have used in the past with Windows.
The front microphone input port is an excellent addition. While it’s audio quality is highly dependent on the microphone quality on your headset, it worked properly without any added background hissing.

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Sound
It’s safe to say that the K5 is able to drive most common headphones and headsets to excessive listening volume with ease.

I threw quite a few of my headphones at it to see what would stick and it was able to drive all of them to uncomfortably loud listening levels, even on my Hifiman HE-500 and Sennheiser HD650, however it struggled to render the sound competently when compared directly to more powerful amplifiers.

I noticed it especially failed to produce convincing dynamics with large planars, which are notoriously power-hungry, and with some more demanding dynamic headphones like my JVC HA-DX1000 it was not able to control sub-bass texture with authority.

With most headphones it sounded somewhat ‘weak’ despite the adequate volume output.

I think one of the main factors for this evaluation is that the K5 Pro appears to be on the leaner side of neutral, with upper mids being slightly more forward and bass slightly reduced compared to other amps I own. Of course this evaluation only takes into consideration the units performance when no tone control is applied.
I measured 3 random dynamic headphones (volume matched) on the K5 Pro and on my NFB11.28TXO (unmodified), and the results confirmed my evaluation consistently despite variation in headphone output load.

I think this is neither a good thing or a bad thing – you only have to ask yourself how much does this matter to you on a unit that comes with it’s own tone controls. Personally, it matters little.

Measured with miniDSP EARS.


With the bad out of the way, here comes the good news! This DAC seems to excel with sensitive dynamic driver headphones. The differences between this unit and more expensive units become far more incremental.

The biggest surprise for me was how well it took to driving my Sony MDR-SA3000.
This headphone in combination with the K5 Pro sounded practically no different to my NFB11.28TXO, but the really impressive part is that adjusted treble and bass with the K5 sounded less compressed and more lively than the NFB11.28TXO with Equalizer APO – a common drawback of using digital EQ.

Those who know the SA3000 are aware that is is a detail and treble-monster with a rather weak bass response. Correcting those ‘flaws’ to my taste on the K5 Pro was so simple and brought my SA3000 to another level of enjoyment.

For context here are the measurements of the Sony MDR-SA3000 through the K5 Pro with various EQ settings.
Measured with miniDSP EARS.


In practice, the EQ offers adjustment up to around +/-15dB in the bass and about +/-9dB of treble.
In my opinion this is more than enough for most headphones, as demonstrated by it easily ‘correcting’ the notorious SA3000.
The ‘correction curve’ of both treble and bass do not radically intrude into the midrange and is an excellent additional feature at this price point.

However, I don’t recommend using the tone controls to their extremes. I noticed that maximum bass volume will introduce mild distortion.
For extreme bassheads I would still recommend using EQ APO as a primary source of tone control.

Also, the minimum bass volume seems to introduce some artefacts, however at this greatly reduced volume, you likely wouldn’t hear any of those artefacts anyway.

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Conclusions
There is a lot to like about this little guy.
It’s a really well thought out selection of inputs, outputs and functionality to get anyone started on their audio journey.

I found that most of it’s drawbacks are largely due to me being spoiled by bigger amps, and it also proved to me that even a small DAC can still synergize with the right equipment and bring a lot to the table.

It’s great to see tone controls on a tiny amp at the entry level.

This is the kind of feature that would prevent people from spending and spending on many different headphones for every different album, genre and video game. Instead you just need to dial in your preferred tone setting, or adjust as you go, without having to reach for a different headphone for every occasion.

Sure, it’s not a reference grade unit, but I could certainly have used this 15 years and 400 headphones ago, and I would have no trouble making a recommendation. If absolute peak audio quality isn’t a concern, even to seasoned audiophiles who just need a small, affordable and versatile unit for their gaming console, this is certainly an option worthy of consideration.

TLDR version on YouTube: TDLR - Fosi Audio K5 Pro

The K5 Pro has been sent to me directly by Fosi Audio. I have no affiliation with Fosi Audio and I will do my best, as always, to be as unbiased and sincere as humanly possible, however, it is always good to note that this device has not cost me anything to try out.

You can find the Fosi Audio K5 Pro on Amazon in almost any country, so there is really no need to head over to my blog to see any links, which are always non-affiliate anyway.

Unless, of course, you want to practice your español and read the Spanish version (link to blog at the end of this post).

To avoid being repetetive in my reviews, you can find all the info about how I create the reviews, equipment used, how I receive the products and how to interpret my reviews by visiting: About my reviews



Intro…

Fosi Audio is a brand that pops up regularly on Amazon (and AliExpress) when searching for budget audio gear. Personally I have never tried a Fosi Audio product, although I have come close to ordering one on a few occasions but something else always popped up and it got pushed back.

They have quite a few different models, covering things like 2.1 amplifiers, subwoofer amplifiers, tube hybrid amplifiers etc. And amongst those is the K5 Pro, a device labelled as a “Mini Stereo Gaming DAC”, which comes in at around 90€ (on Amazon Spain) and features a headphone output, amongst other things.

Therefore, when Fosi reached out recently and asked if I would be interested in trying out and possibly reviewing any of their products, I said that I would be interested in giving the K5 Pro a whirl and seeing what they could offer in this budget priced category.

Before getting into the review, I have to say that I was surprised at the details that Fosi share about the product. Usually we find the most basic of specs published and not much else, yet Fosi actually list the chips used and the THD, SNR, etc. I’m afraid that I don’t have the equipment to check that what they publish is correct but they do seem to be at least realistic, on paper, for a device of this size and price.



Presentation…

The box in which the K5 Pro arrives doesn’t exactly scream quality but it is at least colourful and is not just a simple brown box with text on it.

Opening the box, we find the device, a USB A to USB C cable (with a removable adapter to convert it to USB-C to USB-C), a 4pin 3.5mm female to dual 3.5mm TRS cable (to use a 4 pin headset with the two separate input/outputs on the device), an optical cable and a fairly decent user manual.

I have to say that the contents are more than I expected at this price, especially in comparison to other devices at similar (or more expensive) price points.



Build and aesthetics…

The K5 Pro is a very small device, not quite palm of the hand but not much bigger either. The enclosure is completely made from metal, in a dark grey finish, with metal knobs in a silver colour.

The unit seems to be well built, with no obvious flaws, and the aesthetics are quite good (in my opinion) being simple yet not looking cheap.

The included cables are also of a decent quality. They are nothing special, nor are they high end, but they are no worse than the accessories included with many other products.



Functionality…

The K5 Pro is fairly simple but does have quite a few features for a small, budget device.

Starting on the back, from left to right, we have a USB-C input (for data and power, so this always news to be connected even when using other inputs), an optical input, a digital coax input and RCA analog outputs. Each of these is clearly labelled.

Moving around to the front, again from left to right, we find a 3.5mm TRS headphone output, a 3.5mm TRS microphone input, a bass knob, a treble knob and a volume knob that is also a push button. Above the 3.5mm input/output, we have a small row of (blue) LEDs that show which input is selected.

To turn the device on, the volume knob must be pressed and held for a few seconds and the the blue light above USB will light up to show the device is powered on and in USB input mode. The device always turns on in USB mode, independently of which input was selected before turning off.

Once the K5 is on, a short press of the volume knob cycles through the inputs (USB - Optical - Coax) with the corresponding light illuminating (and a click inside the device). While I did test all of these inputs, I mainly stuck with USB as I used this on my desk at work.

There is no way to turn off or bypass the EQ controls (Bass & Treble) so turning them to center should give a neutral response, although that is not always the case with devices like this. Therefore, I took a quick measurement of the output with the knobs centered:



Finally, before getting to sound, let’s mention the part that makes this device stand out from other devices that I have reviewed at similar price points… the mic input.

The mic quality running through the K5 Pro is not the best but it is far from terrible. Voices are clear and easily understood, depending on the microphone used of course. I tested both the inline mic on the Koss PortaPro (Drop edition) and a fairly cheap lapel mic, both with decent results. No, I wouldn’t recommend this if you are planning on recording voice overs or a new single, but for chatting or gaming, it should be fine.



Sound…

Let me start off by mentioning power, as this little device claims it can output 1W at 16 Ohms, which is a lot of power for such a small device. For comparison's sake, the JDS Labs Atom claims 1W at 32 Ohms and that is an amplifier that I very rarely need to push above 50%. In the case of the K5 Pro, using the KPH40 which are 60 Ohms (the K5 claims 300mW at 64 Ohms) and I found that I could max out the amplifier without going deaf. Yes, it was loud, but it certainly wasn’t unbearable (at least for short bursts) so I am not overly confident that this device can actually produce the power it claims.

There is also the subject of distortion, which, with hard to drive headphones, can start to be audible as we get towards the ¾ mark on the dial. It is not terrible but it is noticeable, so, again, while I don’t have the apparatus on hand to measure the numbers, I think they may be a little “over confident” in their claims. Added to this we have a bit of background hiss which becomes apparent with sensitive IEMs when moving past 50% on the dial, with 75% being audible on almost all IEMs and headphones.

Let’s talk about one last negative before moving to the positives, getting all the bad news out of the way at once. In the case of planar magnetic headphones, at least the ones I have on hand, the K5 Pro does struggle. It is to be expected as it is powered by USB and I doubt that there is much in the way of current going on, but as soon as things like the HE400se are pushed with some strong and fast bass, you can tell that this little amp is struggling to keep up.

So now on to the good. The performance of this little device is actually quite good. The sound signature seems to be neutral but without being too harsh, with a slight smoothness to the overall sound. With the dials set to the center position, I find the sound to be enjoyable, making things just have that little hint of warmth.

Then we have the EQ options, which do offer quite a bit of range, possibly more than is needed. With just a slight turn of the bass dial, the increment in the low ranges is quite noticeable, adding that extra thump when needed. The treble dial seems to be a little less apparent. By this I don’t mean that it is not more than enough when needed, just that the changes aren’t quite as exaggerated as with the bass knob.

Here is a quick graph showing the results in different positions on the knobs:



This obviously allows you to tailor the sound to your preferences and, while overdoing it will deteriorate the sound, should be plenty for those who just want a little bit of extra flavour, especially when swapping between game playing, music listening and video content.



Conclusion…

The Fosi K5 Pro is a good little box that offers decent performance at a very reasonable price point. The obvious question that I think people will ask is how it fairs against something like the iFi UNO, which is priced similarly and is by a brand that is probably better known in the audio realm.

Well, as far as sound goes, I do feel that the UNO is slightly cleaner and maybe offers a little more detail (although the differences are minimal in this regard), especially when pushed more towards the upper ranges of the dial.

Yet, where the UNO offers 3 specific EQ presets for you to choose, the K5 Pro allows you to tweak the dials to your preference, giving a more personalized approach to how you want your music (or other media) to sound. The Fosi also offers an additional 2 digital inputs, allowing you to feed it from multiple sources (such as consoles and TV’s) if you wish.

Then we have the final function that I feel is missing from the majority of devices in the budget category, a microphone input. This allows you to use headphones of your choice, with or without a microphone, and even add something like a boom mic if you wish. This is something that makes the K5 Pro a very interesting option for gamers and even for those who do a lot of calls from their PC.

All in all, I think that the Fosi K5 Pro is a very interesting device for its price and, although it may not be outstanding just on the audio front, it offers a lot of options for those who are looking for a cheap, compact, all in one device for their desktop.

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As mentioned above and as always, this review is also available in Spanish both on my blog (www.achoreviews.com) and on YouTube (www.youtube.com/achoreviews)

I want to thank Fosi audio for the sample of the K5 pro, as always this is my opinion on it and I've not been paid or influenced by anything other than the music.
https://fosiaudioshop.com/products/fosi-audio-k5-pro-mini-stereo-gaming-dac-audio-for-pc
https://www.amazon.com/dp/B0BFHFSX4C/

The K5 pro come in a good size box so I was surprised to see how small this gaming Amp was, look wise its very attractive gun metal finish with silver knobs. The device is well made and solid. it has more than adequate IO and the Bass and Treble is appreciated as I love physical EQ. The device was powerful to drive my planar headphones and gentle enough to run my IEMs so I am impressed with that already.

The K5 pro sounds clear and transparent with a slight warmth and very good details, it is a vast improvement over standard audio from the source, Nintendo, PC, phones and PlayStation. The k5 pro is more towards the neutral side with the bass and treble on zero but has good dynamics and soundstage as well, I have a few audio-interfaces like the CREATIVE G7 G6 and some others, this little guy best them with power and clarity to my surprise.

Afterthoughts: The K5 pro for Fosi audio is under $100 and hits above its weight limit, has good features and is made well, it definitely will be using this on my switch from now on.