07-13-2011 04:24 PM
Nope. Not for an mp3 player as the class (or speed) of the card is rated on the 'writing to' not 'reading from' speed. This is important if you're using the memory card in a camera for quick recovery when taking multiple shots, but doesn't matter in the least when using it in an MP3 player.
You might notice a slight decrease in the transfer time when loading your card with files from your computer if you're doing it all in one shot with a higher Class card, but it would be it.