I'm assuming you think the HD600 are better overall then? Are they worth 50% more money?
Thanks, and sorry for hijacking the thread.
It all comes down to your preferences, the system, and your hearing. The only way to know for sure which you think is better is to compare the two for a good amount of time. I thought the K612 sounded better than the HD 600 on the system I compared the two on(Woo Audio WA6SE with the Bifrost Uber) but then again the AKG sound also agrees better with my ears than the Senn sound.