For those wondering if AirPort Express supports MP3, AAC, or any other specific file formats, the answer is no. AirPort Express supports Apple's Lossless Compression technology
叛之：
Airport Express 不支援 MP3、AAC 或其他特別格式。
Airport Express 只支援 Apple's Lossless Compression。
iTunes does the heavy lifting. When iTunes plays back standard audio content (AAC, MP3, audiobooks, music streams), it decompresses those file formats and creates what's essentially a raw, uncompressed audio stream. That stream is compressed on the fly using Apple's Lossless Compression, encrypted, and sent to the AirPort Express. AirPort Express decrypts the stream, decodes it, and outputs it in either analog format (...) or as a digital PCM stream (...).
iTunes 的工作量可不少喲
