The Fosi Audio Q4 functions as a dedicated digital-to-analog converter and headphone amplifier, eliminating the need for driver installation or software configuration. USB, Optical, and Coaxial S/PDIF inputs interface seamlessly with computers, gaming consoles, and digital audio sources, while RCA outputs connect to amplifiers or powered speakers. The integrated headphone amplifier delivers 160mW RMS at 32 ohms with minimal distortion, accommodating impedances from 16 to 200 ohms across most professional and consumer headphones. Independent bass and treble controls enable personalized tonal shaping, while the preamp functionality allows volume management for desktop systems. The compact chassis processes high-resolution audio up to 24-bit/192kHz with low jitter, preserving bit-perfect signal integrity. Output protection circuitry safeguards connected equipment from transient damage, making the Q4 an ideal solution for gamers and audiophiles seeking transparent digital conversion and headphone amplification in a minimalist desktop form factor.