I know the AKG K240 and I can tell you they sound quite 'flat'... I believe they are good for someone who is DJ'ing perhaps. Although this one is rugged, there are far more dynamic and transparent headphones out there.
I don't have extensive listening experience with the Senn HD600, but I CAN say that it's a MUCH better headphone than the AKG K240.
I don't have extensive listening experience with the Senn HD600, but I CAN say that it's a MUCH better headphone than the AKG K240.