I have a texture pack that changes the music disc music to different music and it works fine. But I was experimenting with subpacks and having the sounds inside a subpack. But it doesn't work, it doesn't play anything. Steps to recreate have texture pack that changes the .ogg's of the disc's music. Create sub packs properly, put the "sounds" folder in a subpack. Now when you try to play a disc it will not play any music. I really think the sub packs future is powerful but it need to be sorted out better.