"The Bottlehead Crack is a superb introduction into the world of DIY audio. The parts quality is very good, the documentation is truly excellent, the Bottlehead forums provide fantastic peer-to-peer assistance, and construction is very easy. The Bottlehead Crack is an outstanding first project for the novice audio DIYer. The big win, however, is that once you've finished your build, you'll have a fantastic sounding amp for your high impedance headphones. I simply can't recommend the Bottlehead Crack highly enough.
— Tyll Hertsens, Innerfidelity