Ok, i'm pretty convinced i have a standard pair of premium 250s now. thanks everyone. Although i am still confused about the headband being so tight.... no matter. Thanks guys! And enjoy your 600ohm pairs! 

Thanks ALTANertive. I did what you said using the settings shown in the picture here: http://img232.imageshack.us/img232/8717/wp000278.jpg (i hope they are correct) And i got a reading of 237 for both left and right channels. Does this mean i have a 250 ohm model? Thanks again   And...

Brooko, Stv014, thank you very much for the help. ALTANertive, while i do own a multimeter, i am not sure if i trust myself with it, especially since i have read that it is possible to do harm to the drivers. So maybe the volume thing can be explained, but i am still unsure as to why it clamps...

Hi guys. I bought a second hand pair of 880/600ohms (or so i am told). I have my doubts because of the following reasons...   1. They are tighter than my pair of DT990 32ohms, not as comfortable 2. There is no engraving on the plug end to indicate impedance rating 3. They work great...