Java Plugin Not Visible In Firefox

I should explain that I excluded players such as VLC or Media Player Classic because whilst those can play music well, they are mainly geared to playing video and don't have great music library management functionality. You can create playlists for VLC, for example, but not browse though an entire music library, picking which tracks to play as the mood takes you. I also didn't review DeadBeef, because its Windows version currently has no means of displaying Album Art. When its Windows offering matches the functionality of its Linux versions, I may have a second look at DeadBeef.