Layout, design and features …
The K7 is a universal device that takes samples from digital signals and converts them into an analog waveform that is audible to the human ear. The analog waveform is in turn amplified with an external power supply to feed powerful headphones. 2.1W (balanced) and 600mW (unbalanced) may not sound like much power, but an average pair of headphones can be powered by a smartphone with less than 100mW.
However, the power requirement has increased due to the use of magnetostatic drivers in headphones. Theoretically, smaller loudspeakers can also be operated via RCA.
Essentially, however, Fosi Audio advertises the device as a music and gaming solution in the context of headphones. A 3.5mm jack plug is used via the PO connection. The balanced Pentaconn connection (BAL = balanced) not only has a higher maximum output, but also theoretically has less interference due to additional conductors with inverted signals. A separation of channels in relation to the dimensions also works wonders with regard to common mode interference. However, we are unable to assess whether this is natively present internally in the amplifier. A headset can be attached using the supplied splitter cable for microphone and headphones.
From left to right, there are all kinds of connections on the back, namely RCA for desktop speakers, the connection point for the Bluetooth antenna, coaxial and optical input, USB-C and finally the power supply.
The buttons are used to select different modes, the level of which is adjusted using the controls. The controls can be adjusted in small, noticeable steps and appear somewhat fragile, as they wobble a little.
It should also be mentioned that the small feet on the back are only glued on. In terms of workmanship, the device does not quite meet its price claim.
Fosi Audio K7 DAC/Amp Practical testing …