m4a
M4A is the reason your iPod sounds like it's been underwater. It's a file format that iTunes uses because it’s lazy and it thinks it’s fancy.
My iPod sounds like a cat walked through a blender and it's all because of M4A.
My friend's playlist was perfect until it turned into M4A and now it's just noise.
I tried to play my favorite song on M4A and it sounded like my math teacher’s voice.