Newbie Question Alert! What impedance level from Hi to Lo-Z?

[Jahn]

I was reading up on the DT770s - and there are 3 different impedances for them - 600, 250, 80. 600 is obviously High Impedance Territory. You could probably make an argument for 250 being high as well. But is 80ohms a Low-Z can? What ohms do we need to be at to be considered High-Z versus Low-Z? I just want to know if my poor Low-Z Cmoy can drive an 80 ohm DT770 - because all of the grados (including my alessandro MS-1) all fall below that impedance and are Low-Z cans for sure - and my Cmoy drives them to my liking.