Sam writes –
A few weeks back I wrote up a blog about the Doublet Headphone Amplifier which lets two people listen to the same audio source with independent volume controls. I got so many emails from folks who were interested in building one that I decided to make another run of the printed circuit boards – and they’ve arrived!
If you want one of the PCBs, email me with your mailing address and I’ll drop one in the mail to you at no charge. You’ll have to supply the parts and the Altoids tin.
Doublet amplifier – Link.