Definitive Technology (sometimes referred to as Def Tech)[1] is an American unit based in Vista, California, of the Sound United division of electronics company DEI Holdings, that designs, develops and sells home theater audio systems, soundbars and headphones.

The company was founded in Owings Mills, Maryland[2] in 1990 by former Polk Audio founder Sandy Gross, along with Don Givogue and Ed Blaise.

Directed Electronics was founded by Congressman Darrell Issa and specialized in car alarms and radar detectors.

[2] Sandy Gross became President of the company's newly formed audio division.

[6] In April 2013, the company combined Polk, Definitive Technology and the Boom Movement brands into a new division called Sound United.