They have big nice TVs that you can plug playstations into, video cameras, etc. This means that if you have the appropriate cable or a PSone then you can play CDs through the telly speakers or your MP3 player through the inputs on the side. I did see someone had a cable that fitted into their iPod and had three oupt cables into the TV. I think you might get away with a single cable that splits into two CD phono plugs.
Anyway, a PSone is usually lighter than speakers/portable CD player so I thought this might be of interest to those of you going next time.