Knight Audio Technologies (KAT) is a UK-based boutique audio company run by Nigel Knight, specializing in hand-built guitar amplifiers, treble boosters, and related accessories. The company was originally conceived in 2008 as Fryer Sound Ltd, a partnership between Nigel Knight and Greg Fryer that manufactured an affordable range of factory-built Brian May-endorsed treble boosters, and was renamed Knight Audio Technologies Ltd in 2010 following a change in ownership.

KAT is best known for its close association with Queen guitarist Brian May. Its catalog includes the officially licensed Deacy Amp replica — a reproduction of the unorthodox transistor amplifier built from a discarded hi-fi circuit that May famously used on Queen recordings — as well as the Studio-One, a hand-built three-valve amp modelled closely on May's 30-watt AC30-derived rig that produces just over one watt of clean output. The company also makes a range of treble boosters, including the KAT STB (Strap-Mount Treble Booster) originally designed for May to work alongside his strap-mounted wireless transmitter, and the KAT RED-18, along with speaker upgrades for the discontinued Vox VBM-1 Brian May Special amplifier.

Beyond May, KAT has built gear for a range of rock and alternative guitarists, with past customers including James Dean Bradfield of Manic Street Preachers and Ray Toro of My Chemical Romance. The brand occupies a niche corner of the market, with small-batch, hand-wired production aimed at players chasing the specific sonic fingerprint of classic British rock tone.

Knight Audio Technologies has 3 products cataloged on Equipboard, including Boost Effects Pedals and Guitar Preamp Pedals. Their gear is featured by 1 artist, with the strongest followings in Rock. Notable users include Brian May.