The Mini³ portable stereo headphone amplifier
Archimago's Musings: Retro DIY Headphone Amp - The Audio Amateur, Gary A. Galo design, built by Mitch Barnett circa 1991.
WHAMMY Headphone Amplifier – Jeremy Young Design
DIY portable headphone amplifier based on an INA1620 chip and TPS65135 - Daumemo
NwAvGuy: Cmoy eBay Headphone Amp
Circuit-Zone.com - Electronic Kits, Electronic Projects, Electronic Schematics, DIY Electronics
Build a Headphone Amplifier — Times 3! | Nuts & Volts Magazine
DIY IRF610 MOSFET Class-A Headphone Amplifier Project
Circuit-Zone.com - Electronic Kits, Electronic Projects, Electronic Schematics, DIY Electronics
DIY Classic 47 Headphone Amp
DIY USB Stereo Headphone Amplifier | Hackaday
DIY "Butte" Headphone Amp
A Very Modern Tube Headphone Amplifier | Hackaday
Build Your Own Headphone Amplifier For Under $30 - The Kuosch NS-01 - Headphonesty
Make Your Own Headphone Amp - YouTube
Looking for nice sounding headphone amp DIY kit | Headphone Reviews and Discussion - Head-Fi.org
DIY Hi-Fi: Class a Hybrid Headphone Amp : 6 Steps (with Pictures) - Instructables
Pocket Class A DIY Headphone Amp by XRK971 – Audio Primate
Build a Headphone Amplifier — Times 3! | Nuts & Volts Magazine
DIY Whole HV1 A1 Class A headphone amplifier kit ( amp kit + case + transformer) | eBay
Audiologica
NwAvGuy: QRV09 DIY Headphone Amp
WHAMMY headphone amplifier - diyAudio Guides
HA-S - NUTUBE HEADPHONE AMPLIFIER KIT | KORG (USA)
