Before you drop $300 on a fancy celebrity endorsed set of headphones, you might be better served trying the iWOW-U from SRS Labs and your existing headphones. That's what I did, with a $20 pair of Sony headphones and the sound quality was significantly better. The iWOW-U is a 3.5mm extension cord but with a twist. It includes a powered amplifier that enhances the sound quality and does a great job of stereo separation... I was skeptical, but the improvement was immediately noticeable and I am a tough cookie to please.
I'm looking forward to bringing this unit on my next flight to see how it helps in that environment. Speaking of environments, the unit has different modes, headphone, car stereo, and of course, enhancement off, which is not mute, but just cuts off the enhancement. It's a great way to test the difference between sound quality with and without the unit.
As noted earlier, the iWOW-U is a powered unit, so it lasts about five hours. In the car, you could plug a cable into the microUSB port and connect it to a car charger, for indefinite use. The U stands for universal, so it works with any audio source. SRS also offers the iWOW-3D which is a unit that plugs directly into the 30 pin port of any iOS device, which also powers the unit. Taking a cue from Apple, all of the units can be customized with multiple color faceplates to match your iPod nano for example.