With all of those amps the 250 ohm will sound just as good as the 600 ohm. We've been over this many, many times over the last few pages. The 600 ohm version works better with high output impedance amplifiers like OTL tube amps. Otherwise they are essentially identical in sound though some say the 600 ohm has very slightly smoother treble (others say the opposite, that the 250 ohm has slightly smoother treble, so it could very well just be driver variance). The only reason for you to go to the trouble and expense of selling your 250 ohm and getting the 600 ohm is if you plan on using something like an OTL tube amp. Even then you might find that the difference is negligible. The only other difference is the clamping force which is slightly tighter on the 250 ohm Pro. Oh, and the 250 ohm Pro comes with a coiled cable while the 600 ohm Premium would have a straight cable.
TL;DR: Forget about it. Your 250 ohm Pro will sound just as good as the 600 ohm version would. Its not worth the trouble to chase after the 600 ohm superiority myth if you've already got the 250 ohm Pro.
Thank you, i much needed peace of mind, but now considering i have onboard audio. Should i get a creatice Zxr or the M&M combo? I do mostly gaming and light music (no audiophile over here)
Also i prefer higher clamping force, i like that my headphones hug me. Coiled cable is fun, not pratical
Edited by douglatins - 6/5/13 at 2:07pm