Alesis
Audio Accessories.
Carvin
dbx Professional Products
DigiDesign
Dolby  
Fostex
Hafler
Mackie  
Maxell  
Monster Cable  
Nady  
Neumann  
Otari
Peavey  
Quantegy  
Sennheiser  
Shure  
Tascam
TDK  

Synthesizers/MIDI

Alesis  
Armadillo Enterprises
E-mu
Kawai
Korg
Kurzweil
Lyrrus, Inc.
Mark of the Unicorn  
Roland
Starr Labs
Yamaha

Signal Processing

Ashly  
Digitech  
Ensoniq
Frostwave Analog Effects
Joe Meek
Lexicon
T.C. Electronic  

Computer Based

Apple Computers  
Applied Magic  
Cakewalk  
DigiDesign 
Emagic
FAQ System Engineering .
Mark of the Unicorn
Midiman  
Opcode  
Real Audio  
Sonic Foundry
Steinberg  
Voyetra  
Wildcat Canyon Software

Guitars

Abyss Guitar Company
Carvin  
Danelectro
Ernie Ball
Fender
G & L Guitars
Gibson
Gretsch
Guild
Ibanez
Jackson
Jim Dunlop
Martin Guitar Company
Mesa Boogie
Paul Reed Smith
Peavey
Seymour Duncan
Steinberger
Trace Elliot
Washburn
Yamaha