Disclaimer: Please note that I am not an audiophile, and this review does not delve into the technical aspects of the IEMs. My impressions are based on my personal preferences, and others may have different experiences with this product. I also have a very limited experience with audio products so please take this review with a grain of salt.
The Fosi K7 was lent to me as part of a review tour in the Philippines.
Pros
- Powerful and musically impressive
- Great build quality
- Wide soundstage, excellent holographic imaging, definitely immersive
- The built-in tone adjustment for treble and bass is a nice feature
- Loads of input and output options
- Affordable price for the features it brings to the table
Cons
- Despite being advertised as for “gaming”, there is a lack of gaming-specific features.
- There’s a noticeable amount of delay when using Bluetooth for gaming
General Product Details
Package Inclusions
- The DAC/Amp
- DC 12v power supply
- USB-A/C to USB-C cable
- Bluetooth antenna
- 3.5 headphone splitter
- User manual
- Input: Coaxial, Optical, USB-C,Bluetooth,3.5mm Microphone
- Output: RCA, 3.5mm Single-Ended,4.4mm Balanced
- Bluetooth Version: 5.0
- Bluetooth Transmission Audio Format: SBC, AAC, aptX, aptX HD, aptX LL
- Chipset: XMOS XU208+AKM4493SEQ+QCC 3031+TPA6120
- Headphone lmpedance: 16-300Ω
- Input Voltage and Current: DC 12V 2A
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3.5mm Headphone Output
- Rated Power Output: L+ R≥600mW+600mW (32Ω/THD+N<1%)
- SNR: 122dB
- THD+N: 0.0005%
- Dynamic Range: 121dB
- Noise Floor: ≤2.5μV
- Frequency Response: 20Hz-20kHz (±0.1dB)
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4.4mm Headphone Output
- Rated Power Output: L+R≥2100mW+2100mW (32Ω/THD+N＜1%)
- SNR: 121dB
- THD+N: <0.0002%
- Dynamic Range: 121dB
- Noise Floor: ≤ 6.5μV
- Frequency Response: 20Hz-20kHz (±0.1dB)
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RCA
- Rated Power Output: ≥2Vrms
- SNR: 20Hz-20kHz (±0.1dB)
- THD+N: 0.0005%
- Dynamic Range: 121dB
- Noise Floor: ≤3μV
- Frequency Response: 20Hz-20kHz (±0.1dB)
- The body of the K7 is made up of cnc-ed aluminum, while the knobs and buttons are made of plastic. The knobs have tactile bumps per step and have around 20 steps each. The knobs are also clickable and has a tactile bump and an audible metallic click when you do.
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On the front of the K7 are:
- 3.5mm microphone input
- 3.5mm headphone output and
- 4.4mm balanced headphone output
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On the rear of the K7 are:
- DC 12V power
- USB-C input
- Optical input
- Coaxial input
- Bluetooth antenna (input)
- RCA output
- On the top are two 3.5cm stepped knobs and a small 1-inch LCD that shows information on currently used settings and connectivity.
- The left knob controls volume when turned, and toggles gain level when pressed. The right knob controls input mic volume, and tone adustment for treble and bass when turned, and toggles mic mute when pressed.
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Below the knobs and LCD are 5 buttons:
- On-Off/UAC: turns the K7 on and off. If the K7 is on, this button toggles between UAC1 and UAC2
- Input: toggles between the possible inputs
- Output: toggles between RCA and headphones (either 3.5mm or 4.4mm - NOTE that it is NOT recommended to use 3.5mm and 4.4mm at the same time)
- Bypass: overrides the bass and treble tone adjustments if you changed them. Use this to hear the natural sound of the K7
- Tone/Mic: Toggles between bass and treble for tone adjustment, and can also control microphone volume if on UAC1
Setup #1 (PC Gaming)
- Source: PC (thru USB C to A)
- Headphones: Philipa SHP9500
- Games: Overwatch 2, Marvel Rivals, Subnautica
Setup #2 (Mobile Gaming)
- Source: Xiaomi Pad 5 (thru Bluetooth 5.0)
- Headphones: Philips SHP9500
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Games: Wild Rift, AFK Journey, CoD: Mobile, Wuthering
Waves
- Due to a recent ear infection I am opting to use headphones for this review.
- I will be using my iFi nano iDSD LE for comparing, as it’s the only desktop DAC/Amp that I own.
- As much as possible I will be using the BYPASS output as to only hear the natural sound of the K7.
- The K7 heats up quite a bit, but with the power it’s about to output I think it’s normal, especially since it has an aluminum case.
- As a gaming DAC/Amp, the feature that I expected to be there isn’t. It’s called “Chatmix” (like the one on the Steelseries Arctis 5) or GameVoice (like the one on the Soundblaster G8)
- There’s definitely a splitsecond delay when using the Fosi K7 on Bluetooth mode. This is very apparent when pulling the trigger in CoDM and the explosion comes in a little late so I can’t recommend using this on Bluetooth mode.
- As mentioned, the soundstage and holographic imaging of the K7 is excellent! Combined with the easy tone-adjustment of changing the bass, footsteps and in-game skills used in Overwatch 2 and Marvel Rivals was much more easier to hear coming. As a support main in both games, it’s always pesky to know when a Sombra or Spider-man is about to jump you.
- Subnautica is another atmospheric game where you play as a stranded astronaut on another planet, forced to scavenge for your survival mostly underwater. It gets a little too real when you hear the water behind you suddenly bubbling.
- All in all, non-Bluetooth gaming with the K7 is a treat and can give you an advantage if paired with the right headphones, people might even accuse you of using wallhacks!
- Right off the bat, the Fosi K7 sounds strong, orchestral music sound fuller. Musical details and and clarity is excellent.
- The details are clear and holographic, it’s definitely immersive.
- Despite my headphones already being open back and therefore offers some good soundstage, the K7 enhanced that a bit more, and the sound felt wider in comparison to what I already hear from my ifi DAC.
Nitpicks
- I have a keyboard with a knob that I use for volume control and mute/unmute. The K7 at times ignored any changes to the volume as well as muting/unmuting. I installed the provided driver here (link provided to us by Ryan of the Fosi team), but after a while it occurred again.
- The K7 has a 3.5mm microphone input on the front panel. I wish the microphone input was on the back instead, as it’s cleaner.
- The Bluetooth functionality of the K7 is for receiving audio (connect your phone or DAP to it), not transmitting audio (connecting to bluetooth headphones/in-ears). This would have been nicer especially if you have a wireless PCVR setup.
- The 3.5mm microphone input is in the front. Would have been better to have it at the back for less cable clutter in the middle of the table. A USB or XLR input for the microphone would have been nice as well but maybe that’s asking for too much?
Other Notes
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Maximum volume stops at 62. Sounds like a very arbritrary number right? They gave us the following explanation:
Our product manager said that the maximum volume is 62%:
- Limited by the amplification level of the main control chip;
- Based on point 1, if the volume level is designed too fine, the number of rotations will increase.
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The K7 is another device you have to manually turn on after you turn on your PC or console. It won’t turn on automatically since it uses external power.
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I was confused what the UAC 1 and 2 were for at first but here’s the gist: UAC1 (USB Audio Class 1) supports up to 24-bit/96kHz audio with limited bandwidth and broader compatibility, while UAC2 (USB Audio Class 2) will disable microphone input in exchange for higher resolution, lower latency, and better synchronization. UAC 1 is present on the K7 because some consoles like the PS5 don’t support UAC2 yet, which makes UAC1 essential for GAMING DACs.
The Fosi K7 is a functionally versatile but powerful DAC/amp, that punches above its weight. It’s a highly capable HiFi device with a wide soundstage, excellent holographic immaging, and immersive sound. And while it falls short of expectations with regards to gaming features, it’s no big deal as the Fosi K7, even if not marketed for gaming, will still be an excellent choice, especially with the discounted kickstarter price, making it a solid option for audiophiles and gamers looking for a budget-friendly HiFi experience.
I’m definitely looking forward to the next product Fosi makes, hopefully it’s going to have more gamer-centric features!
You can purchase the Fosi K7 here.
