Fosi Audio K7

For those unfamiliar with the brand: Fosi Audio has been producing HiFi audio equipment since 2017, including amplifiers, preamps, DACs, and headphone amplifiers for home use, with a stated focus on sound quality and technical innovation.

Package contents

The K7 comes with an English-Chinese manual, a USB cable with USB-C-to-USB-A adapter, a Bluetooth antenna, a headset adapter cable, and an external power supply. The PSU is notable for being completely silent – no whine, hum, or buzz.

Technical specs and design

Internally, the K7 uses an XMOS XU208, AKM4493SEQ, QCC3031, and TPA6120 chipset. It supports sample rates up to PCM 384 kHz and DSD256 over USB, plus aptX HD Bluetooth streaming at 24-bit/48 kHz. Its fully balanced design and ultra-low distortion (0.0002%) promise clean, detailed reproduction.

The aluminium chassis ensures stability in a compact form factor. A 1.5-inch OLED display aids operation, while buttons and knobs provide quick access to key functions.

Use cases and special features

The K7 works with Windows (driver required), macOS, Linux, PS5 Pro, PS5, Nintendo Switch, tablets, and smart TVs. With aptX HD, aptX LL, and other codecs supported, it also handles low-latency wireless use.

The integrated headphone amplifier includes overload protection and gain stage switching. LDO regulators provide stable power to minimise noise.

In practice – Fosi Audio K7 under the magnifying glass

The solid metal housing makes a great first impression, with good weight and non-slip feet for stability. The controls feel well made, though the rotary knobs have slight play. The Bluetooth antenna fits securely, and the display is clear and informative.

• Front panel: 3.5 mm headphone and mic jacks plus a 4.4 mm balanced headphone output.
• Rear panel: USB-C, optical, and coaxial digital inputs plus RCA stereo output for external speakers/amps. There’s a switch to toggle between headphone and line-out.

While additional balanced line-outs and digital outputs would be nice, space is tight.

Sound of the Fosi Audio K7

The K7 delivers a neutral presentation with no coloration or unnatural dynamic compression. The stereo image is open and immersive. Gain switching makes it easy to fine-tune volume control range. Tone controls for bass (-18 dB to +18 dB) and treble (-6 dB to +6 dB) are effective, though fixed centre frequencies limit flexibility.

Noise? Virtually none. Minimal hiss is only audible in very quiet environments, and input switching is silent thanks to a brief mute.

Practical touches – the K7 runs only slightly warm in long sessions. With high output and gain control, it drives headphones of any impedance easily. The dual USB modes are especially handy:

• UAC 2.0 for Hi-Res playback up to 384 kHz/32-bit and DSD256
• UAC 1.0 at 48 kHz/16-bit, which enables the mic input – perfect for gaming.

A dedicated USB-C mic input would be a welcome addition for streamers.

Conclusion

The Fosi Audio K7 offers a well-rounded package: thoughtful design, versatile connectivity, neutral sound, and high power output. While a few extra outputs would be nice, firmware updates may bring additional features. As it stands, it’s an excellent fusion of HiFi and gaming capabilities, with strong DAC performance, excellent USB functionality, and effortless device compatibility from consoles to computers to wireless streaming.