Since nobody answered my thread, I'll post this again. Hopefully, somebody will see it this time. I really need your help!
In an incredibly lucky event, i stumbled upon the official ultrasone importer for my country. The HFI 550 is 73 euros, the HFI 650 is 77 euros and the Proline 550 (this is an old model from what i've read) is 106 euros. I also sent an email to them asking about the prices of the HFI-580 and the HFI-680, but i doubt i'll get them for less than 130 euros.
I already did some digging and I found out that for my needs (hip-hop /electronica/ some gaming) and specs (xonar DG), the hfi-580 would be ideal. But iirc the HFI-550 should be very simillar sound-wise.
Now for my question: Should i try and gather some more money for the 580/680 or should i buy one of the ones already available? I'm on a pretty tight budget, but if it is worth it, i won't cheap out.
For referece, the HFI-580 runs at ~150 euros in my country.