Eikido the Sennheiser HMEC 46-B-K headset has an audio input in the battery box. This can be plugged into any normal mp3 player and many mobile phones. If you are looking for a general aviation headset with audio inputs the Telex Stratus 50-D is the best available.
While I am not surprised that many on this forum find it impossible to listen to music and keep the aircraft in the air at the same time, the amount of vitriol directed at those of us who do listen to audio / do crosswords / read aircraft manuals while flying seems excessive.
How else am I going to keep up to date on BBC 4's Best of Natural History Radio?