Looking for a portable headphone + amp combo

[barrelz]

Hey guys,

uni just started again and i made the decision to get a decent headphone + amp setup, so i can spend the time between lectures producing.

My budget is ~400€ & i don't really care if i buy used or not.

Had a few headphones in mind:

Sennheiser HD650
Sennheiser HD600
German Maestro GMP400
AKG K-701

I have literally no clue about headphone amps tho, im just looking for something portable here that can drive higher impendance headphones.

Another thing im not really sure about is open back vs. closed back, i would prefer open back due to better sound stage, but im concerned about sound leaking too much.

Since i would also totally use the headphones as reference monitor in my home studio, i still lean towards open back at the moment.

Seriously tho, im thankful for any input on this topic

cheers