iPhone and iPod can’t play .flac format, so we need some converted to convert this format into readable iPhone/iPod. And I will show you how to convert .flac into other audio format (mp3, aac, apple loseless/m4a, wav etc) on Mac OS X. To convert .flac I will give you two free apps that I think so wonderful and east to use. The first App is Max and the Second Apps is XLD

Convert Using Max

• Launch Max, and you'll see File Conversion window (otherwise select "Convert Files" from the File menu.)
• Drag and drop or click on the "+" button to select your .flac files.
• Click on the "Convert" icon to start the conversion.

Convert Using XLD

Before you star convert using XLD, this much better you open XLD App and setup some parameter such as Output Format and many more.

Tutorial Setup XLD App

Then select your files and chose to open with and chose XLD and you’ll see this progress and wait until it done.

XLD Converting Progress

That the best way to Convert .flac into .mp3/.m4a etc in Mac OS X, now you have audio format that suitable for your iPhone and iPod.