D...

 César Diaz

 D & J Electronics

 D&M

 D'Amico FXS

 D'Angelico Guitars

 D*A*M (Differential Audio Manifestationz)

 D-Custom

 D.B. Goods

 D3 Audio Designs

 D67 Audio

 Da Aqua

 DA Electronics

 Dacs

 DAG

 Dallas

 Dallas Pedals

 Dallas-Arbiter

 Damage Control

 Damila

 Dan Armstrong

 Dan Zink

 Dan'Amp

 Dandy Job

 Danelectro

 Danneberg Electronics

 Daphon

 Daredevil Pedals

 Daring Audio

 Dark Cat Workshop

 Darkglass Electronics

 Darrell Mansfield

 Dave Hall Amps (DHA)

 David 69 Effects

 Davidson Effects

 Davoli

 Dawner Prince

 Daytona

 Daytone

 Dazatronyx

 DB Design

 DBJ Laboratories Inc.

 DC Pedal Board

 DC Voltage

 DCLTech

 DDyna Music

 de Lisle

 De Marchi

 De Salvo

 Dead Sea Electronics

 Deaf Audio

 DeArmond

 Death By Audio

 Deathwish Electronics

 Decibel Eleven

 Deco Pedals

 Dédalo FX

 Deep End Effects

 Deep Trip

 Delicia

 Delta

 Delta Lab

 DeMarco Electronics

 Demeter

 Denio

 Dennis Cornell

 Denton Sound Labs

 DenTone Electronics

 Departure Electronics

 Derax

 Deserted Circuits

 Design Retro Works (DRW)

 Design Technology

 Devi Ever FX

 Deviltone

 Dewtron

 DG - DanGuitar

 Dharma Sound

 Diabolical Devices

 Diago

 Dialtone Electronic Effects

 Diamond Amplification

 Diamond Guitar Pedals

 Diamond Skeleton

 Diana

 Dice Works

 Dickinson

 Diederich Electronics

 Dighom

 Digicomp

 Digiplay

 Digisound

 Digisyn

 Digitana Electronics

 DigiTech

 DiMarzio

 Dimavery

 Dimehead Electronics

 Dimmed Light Devices (DLD)

 DingoTone

 Dino's Guitars

 Dinosaur

 Dinosaural

 Diplomat

 Dirk_Hendrik

 Dirtgarden Effects

 Dirty Bird Audio

 Dirty Boy Pedals

 Disaster Area Amps

 Discrete Circuits

 Divided by 13

 Dixi

 Dixon

 DLS Effects

 DMB Pedals

 DNA Analogic

 Do-In Music

 docSanchezFX

 Doctor Tweek FX

 DOD

 Doepfer

 DogsBolloxFx

 Donnerbox

 DooDad Guitars

 Dort Audio Services

 Dot On Shaft

 dp Music Works

 DQC

 Dr Tone

 Dr-No

 Dr. Balls Electronics

 Dr. Blade

 Dr. Green (by Ashdown/Hayden)

 Dr. J

 Dr. Scientist

 Dragonfly

 Dragonfly FX

 DreamTone FX

 Dredge-Tone

 Drive

 DryBell

 DS Electronics

 DST Engineering

 DTS Audio Research & Technology

 DTS Effects

 Dubtronics

 Duesenberg

 Dunwich Amps

 Durham Electronics

 DV Mark

 DVK Technologies

 DW Labs

 Dwarfcraft Devices

 DWJ Boutique Pedals

 DWT Custom

 DynaBoxx

 Dynacord

 Dynamic

 Dynastar Electronics

 Dynavox

 Dytone

 Jack Deville Electronics

 Jim Dunlop

 Recompas