Headphone noob talking here, but I just purchased:
audio-technica ATH R70x open back reference headphones.
Prior to that, I made a lot of music on the Digitone using a very cheap, crappy pair of headphones.
The impedance of the ATH R70x is 470 ohms. I initially thought I wanted low impedance headphones to be compatible with other devices. But then I decided that I was mostly plugging into the Digitone and using the DN as an audio interface for my computer.
I read about the “rule of 8”: the output impedance of the Digitone headphone jack is 55 ohms. Multiply by 8, and the ideal headphone impedance is 440.
So far, I love the ATH R70x. They are very comfortable and light. I cannot compare them to any other nice headphones, but the improvement from my old headphones is huge. For my first project with them, I found myself listening to and responding to a lot of detail (such as isolating and eliminating little transients in sounds) that I hadn’t before.
I suspect these headphones cannot stand being thrown around. I am not going to be testing that suspicion, but the lightweight nature of them makes me think they are delicate.