KICKSTARTER PRICE: $153 (PHP. 8,300.00)

WATCH REVIEW HERE:

PROS:

• The most practical Hi-Fi amplifier I’ve tried
• Fantastic power output
• Clean but lively sound
• Microphone jack support
• Informative OLED screen
• Built in EQ
• Dedicated mute button
• Solid bluetooth support
• Premium metal build quality
• Dedicated buttons for many of the features
• Intuitive controls

CONS:

• Shakey and cheap-feeling buttons
• Not a lot of “gaming” features like app support, multi profile EQ, etc
• UAC 2.0 does not have mic support
• EQ is only limited to high and low shelves
• No LDAC support

WHO THIS UNIT IS FOR:

• People looking for a practical HiFi amplifier
• People who want a feature rich desktop amplifier
• People who want microphone support on their HiFi amplifier

WHO THIS UNIT ISN’T FOR:

• People who want an amplifier with a smaller footprint
• People who want more gaming oriented features
• People who want a simple amplifier

SHORT REVIEW: 

While not as focused as a gaming amplifier, the K7 is one of the most practical amplifiers I’ve ever tried. Mic support, an informative OLED screen and a powerful but clean sound on a sub $200 amplifier is something that was not in my bucket list of 2025, but I’m glad it exists. I really cannot think of one “con” about the K7 besides the fact that its “gaming” features are lackluster compared to its HiFi features. HIGHLY RECOMMENDED!

FULL REVIEW:

We may be too late to explore the world and too young to explore the universe, but we live in a timeline where a desktop amplifier can have great sound quality, sufficient power to even power headphones, microphone support, a crap ton of other features including a dope LED screen all for potentially under $200. 

Shilling aside, the K7 has been a seriously versatile device that has changed my perspective on just how practical yet high quality audio amplifiers can be. I’ve always attributed audio devices like these to be extra effort for little gains, at least for casual use. But I haven’t used a device as my main “source” of amplification as much as I did without feeling like I need to change my entire set-up just to get it to work properly.

So today, let’s talk about the K7 and all of its glory, but also what can be improved to potentially make the ultimate “gaming” desktop amplifier. 

FOSI K7 SPECIFICATIONS:

Chipset – XMOS XU208 + AKM4493SEQ+ QCC 3031 + TPA6120

Maximum Sampling Rate:

• USB: PCM 384kHz – 32bit/DSD256
• Optical: PCM 24/192
• Coaxial: PCM 24bit/192khz
• Bluetooth: PCM 24 Bit / 48kHz

Headphone Impedance: 16 – 300 ohms

Input: Coaxial, Optical, USBC-C, Bluetooth, 3.5mm Microphone

Output: RCA, 3.5mm Single-Ended, 4.4mm Balanced

Bluetooth Version: 5.0

Bluetooth Connection Distance: Less than or equal to 13m

Bluetooth Transmission Audio Format: SBC, AAC, aptX, aptX HD, aptX LL

Input Voltage and Current: DC12V 2A

BUILD AND INTERFACE

The most “gaming” aspect about the K7 is the build and interface. Hell, a friend of mine even said it looked like a DJ booth and I don’t blame them. This rectangular, angled and chiseled look is distinctive to only Fosi with their somewhat industrial designs.

The K7 is, by far, their most “unique” designed amp that I’ve tried as it leans closer to a more futuristic design, similar to what HiBy is doing. This is evident with the orange highlights being placed in a way that looks very eye-catching. 

However, the highlight is that OLED screen, which is something I never knew I wanted in an amplifier, but now I actively look for in my future purposes. It’s such a practical thing to see not only your current connections and decoding, but allow for the K7 to be as feature rich as it is. More on that later. 

As for the quality of the interface themselves, they feel alright. The knobs in particular are a little shaky and the interface buttons feel a little cheap. I would be fine with it if it wasn’t for the fact that the cheaper SK01 has more confident buttons than this. Not to worry, it does feel durable enough for a few years of aggressive volume changes without issue. 

Features

The K7 is jam packed with features that overwhelmed me with just how much I can do with this. Let’s talk about them one by one. 

Built-in EQ

The first thing that you’ll probably play around with the K7 is the EQ. Yes, the K7 has built in EQ which can be toggled by pressing the TONE/MIC button. This brings up the bass and treble values that both go from +12 to -12.

The way that the EQ was implemented here were low and high shelves with the low shelf having a more drastic change than the high shelf, as expected for ear safety. You can drastically change the bass profile without introducing boxiness and bloat as long as the headphones you’re EQing aren’t already bloated to begin with. The subtle treble boost can also add much needed sparkle or cut down energy pretty damn well. This is almost equivalent to adding an impedance adapter on certain IEMs. Ideally, you wouldn’t want to crank the values all the way up or down (especially on the bass), but it’s a nice way to see just how far your headphones can get equalized. This is a decent value and one that should be more than enough for basic adjustments that physical EQ knobs would do. Looks cooler than those, though!

But what if you don’t want to do EQ but you also don’t want to reset the profile you have? Bypass mode! It’s a dedicated button that allows you to disable the EQ without needing to reset the values. Once you want to go back to your EQ profile, just press that bypass button again!

It would have been nice for more profiles to be added in order to just swap between profiles depending on the vibe/headphones you’re pairing the K7 with, but the bypass mode is nice in of itself. 

I should also note that the EQ only works on UAC 1.0 and not on UAC 2.0. I can’t confirm exactly why UAC 2.0 cannot support EQ (and the microphone as I’ll talk about soon) as UAC 1.0 seems to exist only for backwards compatibility and devices that only support UAC 1.0 like the Nintendo Switch, but as it stands, you’re limited to UAC 1.0 when enabling the EQ. Speaking of UAC;

UAC Button

One thing that has been present in many DACs, including dongles, is the option to switch from UAC 1.0 and 2.0. UAC 1.0, from what I’ve researched, is mostly used when pairing with devices like the Nintendo Switch, but also allows for microphone support in tandem with the audio output.

I first came across this with the Simgot DEW4X with its occasionally working microphone support. The K7 makes the process very linear and easy to understand as all you need to do is press a single button and you’d be able to see on the OLED screen whether you’re in UAC 1.0 or UAC 2.0. 

My only gripe is that, on top of the delay when switching modes which breaks the flow of listening, UAC 2.0 seems to have an odd delay when switching between tracks. I initially thought this was an app thing as I was using MusicBee on Windows, but this also happened in Spotify.

Thankfully, this is only present when switching between tracks and not the transition between tracks. It would have been a massive con for me if it did. 

OLED Screen

I’ve talked about the features of the K7 that use the 1.5 inch OLED screen, but I want to talk about just how practical this thing is, especially if you’re a file junkie and love to know about the sample rate. On top of that, you can also see what connection mode you’re in so you know if the device is broken or you’re just on the wrong connection mode. 

My only gripe is that the sampling rate can only be seen if you’re in UAC 2.0 in USB mode. It’ll only show if you’re in PCM or DSD mode on UAC 1.0 with no information on whatever file you’re decoding. This isn’t really a dealbreaker, but one that I’m curious as to why it wasn’t included.

Regardless, that OLED screen is a standout as I haven’t experienced a desktop amp with such a feature. 

Bluetooth

The bluetooth feature of the K7 is a rather basic Bluetooth 5.0 system that can only decode up to 24bit/48kHz with aptX. While it might seem lackluster, I’d say that it’s perfectly justifiable considering the focus of the device. 

LDAC would have been a nice addition, considering how great this sounds on wired, but it’s not a dealbreaker for me. aptX HD being capable of at most 576 kbit/s decoding is perfectly fine considering most of my streaming is done through Spotify as most of my playlists are there. However, I will acknowledge the purists who want LDAC and unfortunately, the K7 will not suit you. 

Connection quality is pretty good, albeit occasionally stuttering on my PC during normal use. It could be an issue with my bluetooth dongle, but either way, it’s a generally stable connection. 

The main thing I want to point out is the latency being surprisingly good. While watching movies or playing games, I didn’t think the bluetooth delay was long enough to affect my experience. The sound, most of the time, matches my inputs and what happens in front of the screen. This is thanks to the QC3031 Bluetooth chip allowing for a decent bluetooth listening experience. 

Microphone Input

The one aspect that baffled me the most about the K7 was the microphone input. Normally, desktop amps in this category of the audio space lean towards either end of the quality-convenience spectrum. Either you get all the audiophile features or all the practical features.

The K7 combines both of that with the microphone input that seems to be a big part of the K7’s identity, gaming amplifier and all. It comes with a dedicated volume and mute knob that will show on the OLED screen its current volume level. 

The quality of the microphone will depend on the microphone that you pair it with. Pairing it with in-line or boom-style microphones is great as it provides enough power while minimizing distortion, audio bleed and interference. However, audio-bleed (audio from your headphones bleeding into the mic) is still dependent on the headsets that you’re using. 

However, I wouldn’t recommend pairing this with a condenser microphone as it doesn’t really provide enough power to give the condenser microphones the proper amplification. Anyone who’s owned a 3.5mm condenser microphone should be aware of this.

This then brings me to the aspect of the microphone that I’m not that big of a fan of. First is the fact that it’s UAC 1.0 limited. While I understand that UAC 1.0 is necessary to allow for microphone support, it somewhat defeats the purpose of making the listening process linear when you have to switch between UAC 1.0 and UAC 2.0 if you want to use your microphone. 

Another issue that I have that isn’t necessarily a fault of the K7 is that most external microphones and even gaming headphones nowadays use USB for their interface. While there are still a lot of gaming headphones that use TRRS and lapel mics that use 3.5mm make the perfect pairing with the K7, it would have been insane if Fosi had included a Type C Microphone input on top of the 3.5mm microphone input with this. This would have instantly made it a must-recc for literally every single person on this planet. This leaves another USB slot for your PC and makes the K7 a proper all-in-one device. 

Lastly, the bluetooth input does not have microphone support. Not really a dealbreaker, but bummed those who have bluetooth headsets could make the K7 an easy way to minimize the cables to their PC. 

Regardless, I’m not complaining about the fact that the K7 has a microphone input and I am so thankful that Fosi is closing the gap between practicality and audio quality with this. Speaking of audio quality;

SOUND 

Output Specifications

3.5mm

4.4mm

Listening Experience

DISCLAIMER:

I would like to preface this by saying that most of my listening was done on USB UAC 1.0 and UAC 2.0 as well as Bluetooth. This is because I wanted to focus my testing specifically on how I personally use it. I never used the coaxial and the RCA function, but I will make an updated post on how this works. 

The thing that bothered me about amplifiers was just how difficult it is to properly pinpoint the differences between each other as good amplifiers are meant to playback music through headphones with linearity and clarity. Colored amplifiers are for poorly made or tube amplifiers. 

That being said, the K7 sounds clean as hell. While my perspective on how good desktop amplifiers can get changed since I got the SK02, I can’t deny that the K7 has a certain level of cleanliness that not even the SK02 has. 

The best way I can describe how the K7 sounds compared to every other amplifier I’ve used is a really good piece of linen canvas. It’s a clean, flat and linear surface where once you begin to paint, all the colors come to life and blend perfectly when you want it to and stand out when it needs to. 

The K7 is quite literally a blank canvas of an amplifier that, no matter what headphones or earphones you pair with it, you will get the best listening experience you’d have with those headphones. Straight up, it does what a good amplifier does. 

The low end can be tight or punchy, depending on the track and headphones. The mids are consistently clean, nuanced and transparent on tracks and headphones that bring about that clarity and cleanliness. The treble is snappy, lively but smooth and polished on tracks that are equally smooth, but it doesn’t overly emphasize the sharpness on even poorly mixed tracks. Obviously, the headphones are 95% the sound in this equation, but even then the K7 somehow finds a way to make the headphones more enjoyable by not overemphasizing the bad aspects of the headphones more than cheaper or poorly implemented amplifiers.

This cleanliness also allows for your headphones to perform at its best when it comes to their individual technical ability and headphones with impeccable separation and layering will be perfectly played through the K7. I seriously could not find an aspect of the K7 where it sounded “lacking”. 

Power Output

The highlight has to be the power, however. 600mW on 3.5mm and 2100mW on 4.4mm on high gain is literally the most power that I’ve ever had on an amplifier. Both the SK02 and DC03 maxed out at 1400mW and this goes even higher? I don’t even have a pair of headphones that can utilize 2100mW of power! That only means that you will never struggle with driving and pair of headphones here. The impressive part is how well it handles volume scaling for how powerful it is. I’ve had amplifiers in the past that were either too soft or too loud at low volumes and the K7 is not that. It’s not as fine as something like the SK02 where the differences in volume is so fine that most IEMs regardless of impedance and sensitivity will have a perfect volume spot, but it’s good enough. 

Pairing

This makes the K7 essentially a universal pairing with basically any IEM/headphone that I’ve tried. Normally, I’d feel the need to highlight a specific pairing with an amplifier that I review, but the K7 is so versatile and uncolored that basically anything that you want to hear in its full glory and in its best clothing, you’d pair it with the K7. Besides the SK02, I can’t say the same for other amps I’ve tried. 

Noise and Distortion

I didn’t find the K7 to distort even at higher volumes (at least to my hearing capability), however, it does have an occasionally audible noise floor for very sensitive IEMs. It’s not super audible, but having nothing playing in your IEMs makes the noise floor a little audible. 

It’s a seriously good sounding amplifier with enough power for basically anything that doesn’t need a transformer to run. 

COMPARISONS:

vs SK02

I’ve been talking about the Fosi SK02 as a main comparison for the longest time in the review, but how does it really compare?

Well, fundamentally, the K7 is what the SK02 would be if it was buffed 100 times and catered to a more practical market. However, I’m also aware that the SK02 is a completely different product category to the K7.

This is evident with the existence of the K5 Pro, but since I don’t have that, I have to compare these two. 

And realistically, sound wise, the SK02 and the K7 both present music in such a linear yet lively way. It’s neither clinical nor colored and it emphasizes the best aspects of the IEM or headphone that you pair with the amplifier. 

The main sound difference would come down to the difference in output and how the K7 edges the SK02 just a little bit more in cleanliness, particularly in the treble region. 

With the obvious physical differences like the SK02 not having the OLED screen and only featuring a single knob on top of the countless features the K7 has, it’s clear that the jump in price is justified. 

Regardless, the SK02 fulfills the budget-friendly audiophile better than the K7 and the K7 is a far more practical and powerful device for power users and “gamers” 

CONCLUSION:

Every other amplifier and DAC have become irrelevant to me because of the K7. I said the same thing about the SK02 and the K7 did to the SK02 what it did to every other amplifier that I’ve owned. 

The K7 is quite simply the ultimate desktop amp for a person like me who spends most of their time on the desk working or studying. Powerful, feature rich and practical are the best ways I can describe the K7. 

However, that doesn’t mean the K7 is a perfect device. The small nitpicks with the knobs and buttons along with the occasional delays and maybe even the fact that despite being a “gaming” amplifier, it doesn’t really have much gaming features like what other dedicated gaming brands would offer. Lack of LDAC is also a shame, but one that is understandable with how feature rich it already is. But I would argue that the K7 is more catered to practical-minded audiophiles who might be into gaming as well. 

But fundamentally, this is just a really good desktop amplifier. A bit tedious and cable-rich? Yes. But powerful, practical and versatile? Absolutely. That’s what makes the K7 stand out from every other amplifier I’ve tried

Thank you for reading my full review on the Fosi K7. As of the current moment, the K7 is on Kickstarter here: https://www.kickstarter.com/projects/fosiaudio/fosi-audio-k7-gaming-headphone-amp-dac