The "Mastered For iTunes" label is a badge of sonic approval that you see on most major label tracks and almost none from idie and D.I.Y. artists. A new add-on service from DistroKid makes it possible for any artist to get the "Mastered For iTunes" certification.
Apple has a proprietary converter that its made available to select mastering engineers. It's the same converter that’s normally used on Apple’s end to convert tracks from their raw format to a Apple's streamable AAC format.
his makes it possible for mastering engineers to hear how the compressed audio sounds before submitting it to iTunes and other digital outlets. The engineer can tweak the audio to make sure it still sounds good after it's been compressed.
DistroKid’s new MFiT services does just that.
Opt-in, and for a small fee DistroKid ensures that your audio conforms to Apple’s exacting MFiT specifications. An Apple-certified MFiT mastering house will work with each track to your track can be certified MFiT.
More on Apples MFiT specs here.