| D and C Electronics | Vacuum Tubes, Magnetrons and Sockets |
| D.H. Labs | Cables |
| D.W. Fearn Vacuum Tube Microphone Preamplifiers | Tube Microphone Preamplifier, Equalizer |
| Dada Sound Lab | Handwound Transformers |
| Daedalus Audiophile Speaker Systems | Speakers |
| Daily Electronics | Tubes |
| Daiyoung | Retailer |
| Dan Cheever's DIY Audio Site | DIY Tube Audio |
| Danish Audio ConnecT | Audio attenuator, Input Selector, Phono Modul |
| Das Audioforum | German DIY Forums |
| Dasheng | Heat Shrinkable Tubings Material |
| Dave Ewing | DIY Tube Amplifiers |
| Daves World of Things From the Past | Tubes, Tube Radios |
| David Berning | Tube Amplifiers |
| DaVinciAudio | Tube Amplifier and loudspeaker |
| DaviSound | Tube Preamplifiers, Tube Electronics for Professionals |
| Dayton Wright | Tube Amplifiers, speakers |
| DB Elettronica Telecomunicazioni S.p.A. | Tube Electronics for Professionals |
| dBm Pro Audio-Music Services! | Tubes, Tube Amplifier Services |
| DC Components Co Ltd | Diodes, Bridge Rectifiers |
| dc-daylight.ltd | Articles |
| DDDAC 2000 | DIY Tube Amplifiers |
| De FnS Tube Technologies | Tube Guitar Amplifiers |
| Dean Guitars | Tube Guitar Amplifiers |
| Deckorum | Forum |
| Defboo.cmd | Tube Amplifier Services |
| deHavilland Electric Amplifier Company | Tube Amplifiers |
| Deja Vu Audio - Amplifiers | Retailer |
| Delta Studio Amplifiers | Tube Amplifiers |
| Demeter Amplification | Guitar and Bass Tube Amplifiers |
| Demostenes 2000 | Tubes |
| Der Audiotreff im Internet | Forums |
| Der Deutsche Rundfunk | Information about old radios |
| Design Build Listen - DIY HiFi Components & Kits | Cabinets & Hardware, Knobs, Connectors |
| Deyoung mfg. | Magnetic Parts |
| DHTsound.com | Japanese Portal, Parts, Tube Amplifier Kits, tubes, forums, links |
| Diapason | Speakers |
| Die Homepage von H.-T. Schmidt | Tube Collection |
| Diezel by Salwender | Tube Guitar Amplifiers |
| Digitex | Tube Amplifiers Kits, Parts |
| Digitex | Tube Amplifier Kits, Tubes, Speakers, Parts |
| Dinleti Music | Retailer |
| Diodes | Diodes |
| Dipl.Ing.D.Klimo GmbH | Tube Amplifiers |
| Direct Components | Tubes, Capacitors |
| Direct Heated Rob's Home | DIY Tube Amplifiers, Tubes |
| Direct Heating | Sakuma System from Japan |
| Directory of Australian Valve Suppliers | Tubes |
| Dirk Brauner | Tube Microphones |
| Dirty Harry's Tube Amplifier Page | Tube Audio Information |
| Diva Classic Audio - The Soul of Music | Tube Amplifiers |
| Divertech.com | Retailer |
| DIY - Audio - Index page | DIY Tube Amplifiers |
| DIY - Mania | DIY Tube Amplifiers, Forums |
| DIY Audio | DIY Tube Amplifiers |
| DIY audio | Tube Amplifiers Kits, forums |
| DIY Audio & Video | Information, Links |
| DIY Audio Craft | Parts |
| DIY AUDIO=3=3=3 | Tube Amplifiers |
| DIY Cable | Cables |
| DIY Hi-Fi & Tubes | Tubes, Tube Amplifiers KITS, Parts, Books |
| DIY HiFi Supply Forum | Forums |
| DIY Musikding | DIY Tube Amplifier Site |
| DIY Plaza | Forums |
| DIY ZONE | DIY Tube Amplifiers |
| DIYaudio.com - your audio reference | Forums |
| DIYCable.com | Cables, Parts |
| Diyhifisupply | Tubes, Tube Amplifiers KITS, Parts |
| DiySong.com | Forums, DIY Tube Amplifiers |
| DL7AVF Amateur Radio Web Page | Tube Database |
| Dmitry Nizhegorodov's Tube Audio Project | DIY Tube Amplifiers |
| Do It Yourself Forever | DIY Tube Amplifiers |
| Docet hi-fi official web site | Tube DAC's, Kits |
| Dodd Audio | Tube Amplifiers |
| Dominik īs Hammond and Tube amps Page | DIY Tube Audio, Antique Tube Amplifiers |
| DPF audio | Tube Amplifiers |
| Dr. Tube | Schematics, Link List, Tube Database |
| Dr. Z Amplification | Tube Guitar Amplifiers |
| Drawmer | Professional Tube Electronics |
| Dredge | Schematics, Manuals |
| Drifter Amps | Tube Guitar Amplifiers, Restoration, Repair |
| Dromos AudioLab | Tube Preamplifier, Speakers |
| Duncan's Amp Pages | Tube Guitar Amplifiers, Tube Data, Information |
| DuraCap International | Capacitors |
| Dynaco | Tube Amplifiers |
| Dynamic Audio | Retailer |
| Dynatubes | Tubes |
| Dynavox | Tube Amplifiers, Tube CD Players, Speakers |