Found a graph for the Proline 750:
For comparison: ATH-A900:
Its interesting that, no matter which company developed it, all closed headphones seem to suffer from a dive at around 200-300hz.
The proline 2500 looks completely different, more similar to the AD2000 but with massive bass and the same weirdness going on the uppermids-highs as the 750:
Proline 2500:
AD2000:
The ATs look much flatter than the ultrasones. Maybe they are a mix of the AT & Grado soundsignature? Dunno. Ill hear soon i hope. I worry though that the dive at 300hz will be too much for my taste, thats very possible.
I wouldnt mind some grado agressiveness
