I purchase an earlier Overdrive and have since upgraded it to include the dual turboclocks with Hynes regulators. I tried it early on for headphones using the Sennheiser HD800 headphones. Although it was super clear, there really wasn't enough umph to drive the bass to normal levels. It's possible that Steve has changed the output on his latest Overdrive. I use an Eddie Current Zana Deux tube headphone amp.