At the dawn of the transistor era, John Koss Sr. along with partner Martin Lange, designed a set of commercial headphones using World War II military headphones. The stereo headphones used two tiny speakers, chamois pads from old flight helmets and red tubing that looked like licorice. It was 1958 and the stereo business was taking off with the advent of rock-and-roll music. The headphones were called "private listening units."

The Koss Corp. was founded in Milwaukee when Koss was 27 and the first carry-around radios were being sold. Portable radios became possible due to the transistor, the identical device that in miniature form makes up today's high-powered computer chips. Previously people didn't need earphones because radios were heavy devices made from glass and hardwood, vacuum tubes and weighty speakers that plugged into a wall socket and stayed put. However, that changed with the two-pound, plastic, transistorized battery-operated radio and the Koss headphone. Tony Bennett and Dizzy Gillespie were early supporters of the headphones.

Extremely successful, Koss diversified into other consumer electronics. In the 1960s, Koss bought a maker of manual turntables -- just as automatic record changers were taking over the market. It was Sony's introduction of the Walkman cassette player however, that fueled the Koss plunge into financial trouble. In 1980, Koss unveiled the portable AM-FM radio it had been developing but could not compete with less expensive imports. By December 1984, Koss Corp. was $15 million in debt and filed for Chapter 11 bankruptcy protection. The family-run company emerged one-year later, providing headphones as well as a new line of cordless phones that operate on infrared technology. It also has a multimedia line of amplified stand-alone speakers and headphones for computers.