It should display the ohm rating on the plastic part of the 3.5mm plug. If its 250Ω, the plug will be blank. If it's 600Ω, the plug will have 600Ω written on it.

I've heard that some gamer's really like using Beyerdynamic DT990's. Might be a good cheaper alternative?

I personally wouldn't recommend the SHP9500. The imaging and soundstage aren't very good for open backs.

How would you compare the K501 and the K712? Is there a 'better' between those two in your experience? I have a K501, I'm just wondering if it's worth owning the K712 as well.

Definitely get the HD600. The headphone makes the most difference in sound quality, so buy the best headphone your budget can get.

I've owned both the AKG K550 MK2 and Sennheiser HD598 Cs, and currently still own an Audio Technica A900X and Fostex T40RP MK3 (with Denon pads and comfort strap). So you could say I've had very good experience with the headphones you've mentioned. With regards to the A990Z, I haven't heard this...

I don't think that connector will fit. I bought this to use with my T40RP: That narrow gap before the male connector is required to allow it to fit. Hope that helps.

Beyerdynamic T5p?

A pair of AKG K501's

My apologies for kinda hijacking the topic, but I have a similar question. Can anyone compare the K501 to the K712? Is it worth upgrading from the K501 to the K712?

1) Beyerdynamic T5p 2) AKG K501 (with drawheart pads) 3) Sennheiser HD580 (with 600 grills and ZY cable) 4) Beyerdynamic DT880 Premium 250 ohm (headband swapped for Pro) 5) Fostex T40RP MK3 (with Denon pads and comfort strap) 6) Audio Technica A900X Sold: 7) AKG K550 MK2 8) Philips...