Pros: Comfortable, bright sound signature, wide sound stage, trebles crisp, mids smooth and bass adequate.
Cons: They could have used a 3.5MM plug for use with portable DAC's like the E10. Plug adapter gives unnecessary bulk.
These phones are worth the retail price of $249. They have a wide sound stage which gives dimension to music. Clarity is strong enough to notice poorly encoded sound files. These don't require an additional headphone amp weighing in with an impedance of 50 Ohms. While they do sound good without one an AMP/DAC will definitely add depth to the music. On the negative I personally think the 6.3MM jack terminating at the end was highly unnecessary. Instead Sennheiser could have had an screw on jack where the 3.5MM jack can be coverted to a 6.3MM one with a simple screw on adapter as found with the Sennheiser HD 380 Pro.