Help identify with headphones for Steinberg UR22

Steinberg UR22 http://www.steinberg.net/en/products/audio_interfaces/ur_series/ur22/key_features_technology.html
so what do I choose headphones for this model? HELP! SPEC indicated Headphone Maximum Output Level 6mW 6mW, 40 Ohm. It is VERY small. And I wanted to buy a Beyerdynamic DT 770 PRO 250 or 80 Om. With what resistance to choose headphones??

https://www.steinberg.net/forum/viewtopic.php?f=91&t=38580#p248473

This link does not answer my question. Sound card there described CI2+ I not found for her performance headphone outputs to compare with the UR22. My question is - How to choose headphones (ohms and sensitivity), for such a low phones output of the card UR22 (6+6mW, 40Ohm)

UR22 + Beyerdynamic DT 770 PRO 80 Ohms here. The cans run quite underpowered. I often find myself cranking the knob at 2-3 o’ clock.