I’m picking out some headphones for my UR44C. I want to know the max ohms I can go without requiring a headphone amp or sacrificing on clarity/separation. I am not extremely concerned with volume as I listen at low levels.
It probably depends on what you consider “sufficient headroom”. I wouldn’t go above 80 ohms with any desktop interface.
It depends more on the type of the headphone than on the real impedance…
My Beyer DT770pro 250ohm work very well with my UR22.