With the move towards FBW (Fly By Wire) technology, and increasing reliance upon computers to drive vital aircraft services, including the flight control surfaces (it is probable a defective flight control surface is the cause of the Alaska Airlines crash - I use this example to illustrate the importance of flight control surfaces, not that the MD80 series is FBW), the potential for radio frequency interference in modern jetliners is scary. A transient frequency penetrating a poorly shielded wire could cause disaster. It hasn't yet, and studies are hard to come by as they cost a lot of money. But much of aviation safety information has been gleaned "after the fact", i.e. during the accident investigation.
Consumer electronic products are not closely monitored for electrical shielding of their components. Together with day to day use and abuse, these products can produce radio frequencies that, in the past, used to be blamed for navigation and communication glitches (I've witnessed these phenomena first hand). Now and in the coming years, these "glitches" may be more serious in nature.
As stated, CD Discman's use lasers. Lasers produce RF (radio frequencies). These transmissions have the potential to affect vital aircraft systems.
If you NEED to listen to music during your flight, use a Walkman instead.