Fosi Audio is a Shenzhen, China-based consumer HiFi brand founded in 2017 by Ryan Huang. The company specializes in compact, affordable Class D amplifiers, DACs, and preamps aimed at audiophiles looking for high performance at budget price points. Its product catalog covers integrated and monoblock power amplifiers, Bluetooth amps, headphone amps, streamers, and phono stages.

The brand's best-known products include the V3 stereo amplifier and V3 Mono monoblocks built around the TPA3255 chipset, the BT20A and BT20A Pro Bluetooth amplifiers, the ZA3 balanced stereo amplifier, the BT30D 2.1-channel amplifier, and the S3 balanced streamer/DAC/preamp. Several models use Post-Filter Feedback (PFFB) circuitry, a design choice that has drawn attention from measurement-focused communities.

Fosi Audio sells primarily through its own site, Amazon, eBay, and retailers like Apos Audio, Parts Express, and Bloom Audio. The brand has developed a following on forums such as Audio Science Review and the r/fosi_audio subreddit, where its amps are frequently discussed as entry points into desktop and budget hi-fi systems. Coverage in outlets like Wirecutter has further raised its profile outside the dedicated audiophile community.

Fosi Audio has 5 products cataloged on Equipboard, including Power Amplifiers and Preamps. Their gear is featured by 1 artist, with the strongest followings in Electronic, Hip Hop, and Jazz. Notable users include Oliver Crosby / ANDRS.