I’m using DT 1990 Pro headphones (250 Ω). The output is plenty loud. It starts getting too loud at around the 75% master volume, but the manual does list the output at 55 Ω.
I have a ifi Nano IDSD BL for headphone amplification, but I’m not sure if it can be connected to the Digitone, or how, and whether it would even be warranted if possible.
Would be thankful to get some advice.
Cheers.
So, you want to amplify a signal that is already “plenty loud”?
Why?
I’ve read before that “loud enough” does not necessarily mean driven well. The topic has probably been done to death, so I hoped for a quick answer from users with high impedance headphones using Digitone.
It doesn’t seem unreasonable to me to wonder whether there’s any drawbacks using 250 Ω headphones in a 55 Ω output.
Thanks for that info Jukka. I’ll read into it. 
I also have a pair of DT 1990 Pros and was concerned about output levels at the beginning. No problems with Octatrack or Digitakt or any other devices so far. More than loud enough for studio work. My suggestion: just relax and enjoy their fantastic sound. 
That’s reassuring to hear. Thanks handed.
Also, maybe just a note, the output ohms shouldn’t refer to what it can drive. Right? It means impedance.