If you're looking to convert your M4A files to mp3 on a Mac, there are a few options available. You can use iTunes or a third-party program such as LAME. iTunes is obviously the simplest option, but it can be slow and less flexible than some of the other programs. LAME is generally more versatile, but it's also not free. If you're just looking to save a few minutes, using iTunes is probably the best option, but if you want more flexibility or reliability, using one of the other programs may be better for you.