BSS Audio
BSS Audio is Professional Audio Signal Processing
http://www.bss.co.uk/

TC Electronic
World leader in digital signal processing for studios, guitar effects and computer recording. Over 80% of today’s sound processing uses TC Electronic.
http://www.tcelectronic.com/

Image Dynamics
Manufacturer of high-end car loudspeakers and signal processors.
http://www.imagedynamicsusa.com/

Presonus
Signal processors, compressors, limiters, mic preamps, de-esser, equalizers.
http://www.presonus.com/

Cadence
Manufactures car audio amplifiers, speakers, signal processors, and subwoofers.
http://www.cadencesound.com/

Precision Power
Manufacturer of amplifiers, speakers, subwoofers and signal processors. USA.
http://www.precisionpower.com/

Eclipse
Specialist mobile audio, video and navigation products manufacturer
http://www.eclipse-web.com/

Phoenix Gold
Manufacturer of car audio amplifiers, speakers, signal processors, and accessories.
http://www.phoenixgold.com/

Earthquake Sound
Manufacturer of car audio speaker systems, amplifiers, and signal processors.
http://www.earthquakesound.com

Furman Sound
Furman Sound has been producing high-quality, professional products since 1974. Our products fall into two broad categories: the audio and video signal processors (on which the company was founded) and the innovative AC power conditioning and distribution products for which we are best known.
http://www.furmansound.com/