The SR series are a little darker with way less rez than the RS series. If you are serious about headphone listening, I would suggest you have a listen to the RS 2. They are about the same list price as the Sen 600's, but IMO, have better rez, bass and truer to timbre.
However, if I was to choose between 225 or 580's it would be the 580's. But again, I would spend more and get the RS 2's.
However, if I was to choose between 225 or 580's it would be the 580's. But again, I would spend more and get the RS 2's.