The Sennheiser HD 650 is a great headphone with a little bit of sonic ‘magic’ appeal. The attractively priced MassDrop HD 6XX version is a special bargain.
A popular and nice match for the Sennheiser HD 650 / HD 6XX is a vacuum tube headphone amplifier.
The project here was built by Jeremy Young. It was inspired by the Bottlehead OTL headphone amp, but circuit ‘operating points’ were determined to suit a locally made power transformer.Continue reading