Thank you all. I think that the fatigue for the moment seems to be occurring from a combination of strong clamping on my head, but also the upper frequencies which sound a bit harsh. I am absolutely fine with the level of the bass, and I love Tim Buckley, Madeleine Peyroux, Nina Simone and several other voices when they are in the middle frequencies. When voices reach higher frequencies, it does sound piercing to my ears, and I wonder if HD650 would have been a better choice.
In any case I cannot change it now and I will not spend 300 euros on headphones for a long time. The next purchase is going to be a headphone amp to match the 600. Still I am not sure which one, as several good entry level amps seems to be ok for driving phones up to 300ohms (like the 600). But perhaps I should be looking for a balanced output, to be sure that there is enough power? Like Fiio k7 perhaps? Others have written that the meridian explorer (first version) is fine with the 600. But "fine" from "sounding great" is different. I am going to check without the meridian, straight from my macbook pro to see if i can distinguish differences.
A question is if it would be OK, as in -at least safe-, to connect the 600 to the LINE OUT of the meridian, instead of the phone out. An audiophille friend mentioned to me that the quality is much better through the line out instead of the headphone out. Problem is I am not sure if he was referring to a meridian to headphone, or to a speaker connection.
The problem with EQing is that it is software dependent and I would like to have the headphones connected to a digital piano, and other hardware like analogue synths, and a portable player, without messing around with EQs.
