Yes, they are easy to drive, but again, my phone can push them to volume. Does it mean, that there is no reason to buy an amp? Topping A30 can push them on mid gain and it sounds much better than my phone, but again - does it mean i hit the full potential of these headphones? Not even close! These will really show you differences between amps and dacs. Be ready for this, your curiosity will be rewarded.
Now i am pushing them with a integrated class a amp (discrete mosfet transistors, toroidal transformer) from balanced speaker taps with a pcm1974 based dac (class a I/V converters - THS4131 and class a output stage - LME49990).
Yet, i have heard better amps and dacs, just dont have the budget at this moment.