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DACs — Fosi Audio K7
Description, images, technical data and specifications
Fosi Audio K7
Image source — © Fosi Audio
Fosi Audio built the K7 as a combined desktop DAC and headphone amplifier. The company was founded in 2017 and is best known for compact amplifiers. The unit measures 9 x 15.5 x 4.3 cm, and Fosi lists it at USD 199.99 with a 24-month warranty.
Key specs that matter
An AKM AK4493SEQ chip does the conversion, fed by an XMOS XU208 USB processor with precision dual-clock control. The K7 accepts PCM up to 32 bit and 384 kHz and DSD up to DSD256. USB-C carries the full rate range, while optical and coaxial inputs stop at 24 bit and 192 kHz and Bluetooth, handled by a Qualcomm QCC3031 chip, at 24 bit and 48 kHz. Fosi rates the signal-to-noise ratio at 121 dB and THD+N below 0.0002% from the balanced jack, with 122 dB and 0.0005% from the single-ended jack. Frequency response is 20 Hz to 20 kHz within 0.1 dB. Headphone output is 2 x 2,100 mW into 32 ohm from the balanced 4.4 mm jack and 2 x 600 mW into 32 ohm from the 3.5 mm single-ended jack, and the maker gives a supported headphone range of 16 to 300 ohm. The amplifier section pairs two TPA6120 headphone drivers with OPA1612 op-amps. Power comes from an external 12 V, 2 A adapter included in the box, along with a Bluetooth antenna, a USB-C lead with a USB-A plug and a 3.5 mm splitter. Windows needs a driver, while macOS and Linux work without one.
Engineering and use context
Bluetooth 5.0 supports SBC and AAC as well as the aptX family including its HD and Low Latency versions, letting a phone or tablet connect alongside a computer. A 3.5 mm microphone input is included, which lets the K7 act as a single USB audio device for gaming and voice chat on a PC or console. An RCA line output at 2 V RMS or more sends the decoded signal to powered speakers or an integrated amplifier. Operating information appears on a 38 mm LCD screen, and the front has two large control knobs plus five shortcut buttons. The all-aluminium chassis is tilted by 5 degrees towards the user to make the display and controls easier to reach on a desk.
Pairing
The balanced output has the power reserve for planar magnetic headphones such as Fosi's own i5, which carries a 4.4 mm cable in some bundles. The RCA line output can feed a Fosi power or integrated amplifier and a pair of passive speakers, turning the K7 into the digital front end of a small desktop system.
Alternatives
The Fosi Audio K5 Pro is a smaller DAC and headphone amplifier with bass and treble controls.
Key specs that matter
An AKM AK4493SEQ chip does the conversion, fed by an XMOS XU208 USB processor with precision dual-clock control. The K7 accepts PCM up to 32 bit and 384 kHz and DSD up to DSD256. USB-C carries the full rate range, while optical and coaxial inputs stop at 24 bit and 192 kHz and Bluetooth, handled by a Qualcomm QCC3031 chip, at 24 bit and 48 kHz. Fosi rates the signal-to-noise ratio at 121 dB and THD+N below 0.0002% from the balanced jack, with 122 dB and 0.0005% from the single-ended jack. Frequency response is 20 Hz to 20 kHz within 0.1 dB. Headphone output is 2 x 2,100 mW into 32 ohm from the balanced 4.4 mm jack and 2 x 600 mW into 32 ohm from the 3.5 mm single-ended jack, and the maker gives a supported headphone range of 16 to 300 ohm. The amplifier section pairs two TPA6120 headphone drivers with OPA1612 op-amps. Power comes from an external 12 V, 2 A adapter included in the box, along with a Bluetooth antenna, a USB-C lead with a USB-A plug and a 3.5 mm splitter. Windows needs a driver, while macOS and Linux work without one.
Engineering and use context
Bluetooth 5.0 supports SBC and AAC as well as the aptX family including its HD and Low Latency versions, letting a phone or tablet connect alongside a computer. A 3.5 mm microphone input is included, which lets the K7 act as a single USB audio device for gaming and voice chat on a PC or console. An RCA line output at 2 V RMS or more sends the decoded signal to powered speakers or an integrated amplifier. Operating information appears on a 38 mm LCD screen, and the front has two large control knobs plus five shortcut buttons. The all-aluminium chassis is tilted by 5 degrees towards the user to make the display and controls easier to reach on a desk.
Pairing
The balanced output has the power reserve for planar magnetic headphones such as Fosi's own i5, which carries a 4.4 mm cable in some bundles. The RCA line output can feed a Fosi power or integrated amplifier and a pair of passive speakers, turning the K7 into the digital front end of a small desktop system.
Alternatives
The Fosi Audio K5 Pro is a smaller DAC and headphone amplifier with bass and treble controls.
Specifications
Model name
K7
Conversion type
N/A
Engine
AK4493S
DSD compatability
Yes
Parameters
up to 32 bit /384 kHz and DSD256
Frequency response low +/- 3dB (Hz)
20
Frequency response high +/- 3dB (Hz)
20 000
Gain (dBu)
N/A
Output Level (balanced) (V)
N/A
Output Level (single-ended) (V)
N/A
Input Impedance (balanced) (Ω)
N/A
Input Impedance (single-ended) (Ω)
N/A
Output Impedance (balanced) (Ω)
N/A
Output Impedance (single-ended) (Ω)
N/A
Analog outputs
N/A
Signal to Noise Ratio (dB)
121
Total Harmonic Distortion + Noise (% at 22 kHz)
0.0005
Dimensions (mm)
N/A
Weight (kg)
N/A
Official link
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