Koss Corporation is an American company that designs and manufactures headphones. Headquartered in Milwaukee, Wisconsin since 1958, the company invented the first high fidelity stereophones. Koss continues to design and manufacture headphones and audio accessories. John C. Koss founded the J.C. Koss Hospital Television Rental Company in 1953. After a short time Koss was looking for new ideas, and partnered with Martin Lange to eventually develop a stereo headphone. Based in Milwaukee, Wisconsin, United States, in 1991 Koss Audio & Video Electronics started producing and selling consumer electronics products as a separate company in Hazelwood, Missouri, United States. The Koss family owns more than 75% of the firm.