| Antique Sound Laboratory | Tube Amplifiers, Transformers, Parts, Tubes |
| Audiokit | Tube Amplifier Kits, Speakers, Parts, Tubes |
| Audio-Valve | Tube Amplifiers |
| Berning | Tube Amplifiers |
| David Berning | Tube Amplifiers |
| Dodd Audio | Tube Amplifiers |
| EAR-Yoshino | Tube Amplifiers |
| HeadWize | Headphone Resource Site, forum |
| Musical Fidelity | Tube Amplifiers and Electronics |
| Opera Audio | Tube Amplifiers |
| Reussenzehn Hifi | Tube Amplifiers |
| RudiStor Sound Systems | Tube Amplifiers |
| Sennheiser | Headphone Tube Amplifier |
| Sigma Electroacoustics | Tube Amplifiers, Tube Headphone Amplifiers |
| Singlepower Audio | Tube Preamplifiers, Tube Headphone Amplifiers |
| Skorpion - Tube Amps | Tube Amplifiers, Tube Headphone Amplifiers |
| Stax Earspeakers | Tube Amplified Electrostatic Headphones |
| VTA | Tube Amplifiers |
| WooAudio | Tube Headphone Amplifiers |
| World Audio Design | Tube Amplifier Kits from Hifi World |