DEQX
- Digital audio technology for loudspeaker correction, room acoustics compensation and digital crossover. Solve acoustic problems and improve the sound of any system. Australia.
- http://www.deqx.com/

Audio Harmony
- Engineering and manufacturing of six channel and two channels harmonic enhancement device. USA.
- http://www.audioharmony.com/

Audiodharma
- Makes a devices that improved the cable sound quality. USA.
- http://www.audioexcellenceaz.com/audiodharmacablecooker.htm

Audiodesksysteme Glass
- Makes a CD cleaner and improver. Germany.
- http://www.audiodesksysteme.de

Claude Systems Ltd
- Supplier and manufacturer of audio enhancement products and induction loops enabling corporate companies to adhere to DDA legislation.
- http://www.claudesystems.com

Bedini Electronics
- Manufacturers of audio enhancement equipment such as CD clarifier.
- http://www.bedini.com/

AudioPrism
- Makes products such as power and CD enhancement systems, vibration control, and indoor FM antennas. USA.
- http://www.audioprism.com/